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Nature Versus Nurture Essay Conclusion Graphic Organizer

The nature versus nurture debate is about whether human behaviour is determined by the environment, either prenatal or during a person's life, or by a person's genes. The alliterative expression "nature and nurture" in English has been in use since at least the Elizabethan period[1] and goes back to medieval French.[2] The combination of the two concepts as complementary is ancient (Greek: ἁπό φύσεως καὶ εὐτροφίας[3]). Nature is what we think of as pre-wiring and is influenced by genetic inheritance and other biological factors. Nurture is generally taken as the influence of external factors after conception e.g. the product of exposure, experience and learning on an individual.[4]

The phrase in its modern sense was popularized by the English Victorian polymath Francis Galton, the modern founder of eugenics and behavioral genetics, discussing the influence of heredity and environment on social advancement.[5][6][7] Galton was influenced by the book On the Origin of Species written by his half-cousin, Charles Darwin.

The view that humans acquire all or almost all their behavioral traits from "nurture" was termed tabula rasa ("blank slate") by John Locke in 1690. A "blank slate view" in human developmental psychology assuming that human behavioral traits develop almost exclusively from environmental influences, was widely held during much of the 20th century (sometimes termed "blank-slatism"). The debate between "blank-slate" denial of the influence of heritability, and the view admitting both environmental and heritable traits, has often been cast in terms of nature versus nurture. These two conflicting approaches to human development were at the core of an ideological dispute over research agendas throughout the second half of the 20th century. As both "nature" and "nurture" factors were found to contribute substantially, often in an extricable manner, such views were seen as naive or outdated by most scholars of human development by the 2000s.[8][9][10][11][12][13]

The strong dichotomy of nature versus nurture has thus been claimed to have limited relevance in some fields of research. Close feedback loops have been found in which "nature" and "nurture" influence one another constantly, as seen in self-domestication. In ecology and behavioral genetics, researchers think nurture has an essential influence on nature.[14][15] Similarly in other fields, the dividing line between an inherited and an acquired trait becomes unclear, as in epigenetics[16] or fetal development.[17][18]

History of the debate[edit]

John Locke's An Essay Concerning Human Understanding (1690) is often cited as the foundational document of the "blank slate" view. Locke was criticizing René Descartes' claim of an innate idea of God universal to humanity. Locke's view was harshly criticized in his own time. Anthony Ashley-Cooper, 3rd Earl of Shaftesbury, complained that by denying the possibility of any innate ideas, Locke "threw all order and virtue out of the world", leading to total moral relativism. Locke's was not the predominant view in the 19th century, which on the contrary tended to focus on "instinct". Leda Cosmides and John Tooby noted that William James (1842–1910) argued that humans have more instincts than animals, and that greater freedom of action is the result of having more psychological instincts, not fewer.[19]

The question of "innate ideas" or "instincts" were of some importance in the discussion of free will in moral philosophy. In 18th-century philosophy, this was cast in terms of "innate ideas" establishing the presence of a universal virtue, prerequisite for objective morals. In the 20th century, this argument was in a way inverted, as some philosophers now argued that the evolutionary origins of human behavioral traits forces us to concede that there is no foundation for ethics (J. L. Mackie), while others treat ethics as a field in complete isolation from evolutionary considerations (Thomas Nagel).[20]

In the early 20th century, there was an increased interest in the role of the environment, as a reaction to the strong focus on pure heredity in the wake of the triumphal success of Darwin's theory of evolution.[21]

During this time, the social sciences developed as the project of studying the influence of culture in clean isolation from questions related to "biology". Franz Boas's The Mind of Primitive Man (1911) established a program that would dominate American anthropology for the next fifteen years. In this study he established that in any given population, biology, language, material and symbolic culture, are autonomous; that each is an equally important dimension of human nature, but that no one of these dimensions is reducible to another.

The tool of twin studies was developed as an research design intended to exclude all confounders based on inherited behavioral traits.[22] Such studies are designed to decompose the variability of a given trait in a given population into a genetic and an environmental component.

John B. Watson in the 1920s and 1930s established the school of purist behaviorism that would become dominant over the following decades. Watson was convinced of the complete dominance of cultural influence over anything that heredity might contribute, to the point of claiming

"Give me a dozen healthy infants, well-formed, and my own specified world to bring them up in and I'll guarantee to take any one at random and train him to become any type of specialist I might select – doctor, lawyer, artist, merchant-chief and, yes, even beggar-man and thief, regardless of his talents, penchants, tendencies, abilities, vocations, and race of his ancestors." (Behaviorism, 1930, p. 82)

During the 1940s to 1960s, Ashley Montagu was a notable proponent of this purist form of behaviorism which allowed no contribution from heredity whatsoever:

"Man is man because he has no instincts, because everything he is and has become he has learned, acquired, from his culture [...] with the exception of the instinctoid reactions in infants to sudden withdrawals of support and to sudden loud noises, the human being is entirely instinctless."[23]

In 1951, Calvin Hall[24] suggested that the dichotomy opposing nature to nurture is ultimately fruitless.

Robert Ardrey in the 1960s argued for innate attributes of human nature, especially concerning territoriality, in the widely read African Genesis (1961) and The Territorial Imperative. Desmond Morris in The Naked Ape (1967) expressed similar views. Organised opposition to Montagu's kind of purist "blank-slatism" began to pick up in the 1970s, notably led by E. O. Wilson (On Human Nature 1979). Twin studies established that there was, in many cases, a significant heritable component. These results did not in any way point to overwhelming contribution of heritable factors, with heritability typically ranging around 40% to 50%, so that the controversy may not be cast in terms of purist behaviorism vs. purist nativism. Rather, it was purist behaviorism which was gradually replaced by the now-predominant view that both kinds of factors usually contribute to a given trait, anecdotally phrased by Donald Hebb as an answer to the question "which, nature or nurture, contributes more to personality?" by asking in response, "Which contributes more to the area of a rectangle, its length or its width?"[25] In a comparable avenue of research, anthropologist Donald Brown in the 1980s surveyed hundreds of anthropological studies from around the world and collected a set of cultural universals. He identified approximately 150 such features, coming to the conclusion there is indeed a "universal human nature", and that these features point to what that universal human nature is.[26]

At the height of the controversy, during the 1970s to 1980s, the debate was highly ideologised. In Not in Our Genes: Biology, Ideology and Human Nature (1984), Richard Lewontin, Steven Rose and Leon Kamin criticise "genetic determinism" from a Marxist framework, arguing that "Science is the ultimate legitimator of bourgeois ideology [...] If biological determinism is a weapon in the struggle between classes, then the universities are weapons factories, and their teaching and research faculties are the engineers, designers, and production workers." The debate thus shifted away from whether heritable traits exist to whether it was politically or ethically permissible to admit their existence. The authors deny this, requesting that that evolutionary inclinations could be discarded in ethical and political discussions regardless of whether they exist or not.[27]

Heritability studies became much easier to perform, and hence much more numerous, with the advances of genetic studies during the 1990s. By the late 1990s, an overwhelming amount of evidence had accumulated that amounts to a refutation of the extreme forms of "blank-slatism" advocated by Watson or Montagu.

This revised state of affairs was summarized in books aimed at a popular audience from the late 1990s. In The Nurture Assumption: Why Children Turn Out the Way They Do (1998), Judith Rich Harris was heralded by Steven Pinker as a book that "will come to be seen as a turning point in the history of psychology".[28] but Harris was criticized for exaggerating the point of "parental upbringing seems to matter less than previously thought" to the implication that "parents do not matter".[29]

The situation as it presented itself by the end of the 20th century was summarized in The Blank Slate: The Modern Denial of Human Nature (2002) by Steven Pinker. The book became a best-seller, and was instrumental in bringing to the attention of a wider public the paradigm shift away from the behaviourist purism of the 1940s to 1970s that had taken place over the preceding decades. Pinker portrays the adherence to pure blank-slatism as an ideological dogma linked to two other dogmas found in the dominant view of human nature in the 20th century, which he termed "noble savage" (in the sense that people are born good and corrupted by bad influence) and "ghost in the machine" (in the sense that there is a human soul capable of moral choices completely detached from biology). Pinker argues that all three dogmas were held onto for an extended period even in the face of evidence because they were seen as desirable in the sense that if any human trait is purely conditioned by culture, any undesired trait (such as crime or aggression) may be engineered away by purely cultural (political means). Pinker focuses on reasons he assumes were responsible for unduly repressing evidence to the contrary, notably the fear of (imagined or projected) political or ideological consequences.[30]

Heritability estimates[edit]

Main article: Heritability

It is important to note that the term heritability refers only to the degree of genetic variation between people on a trait. It does not refer to the degree to which a trait of a particular individual is due to environmental or genetic factors. The traits of an individual are always a complex interweaving of both.[31] For an individual, even strongly genetically influenced, or "obligate" traits, such as eye color, assume the inputs of a typical environment during ontogenetic development (e.g., certain ranges of temperatures, oxygen levels, etc.).

In contrast, the "heritability index" statistically quantifies the extent to which variation between individuals on a trait is due to variation in the genes those individuals carry. In animals where breeding and environments can be controlled experimentally, heritability can be determined relatively easily. Such experiments would be unethical for human research. This problem can be overcome by finding existing populations of humans that reflect the experimental setting the researcher wishes to create.

One way to determine the contribution of genes and environment to a trait is to study twins. In one kind of study, identical twins reared apart are compared to randomly selected pairs of people. The twins share identical genes, but different family environments. In another kind of twin study, identical twins reared together (who share family environment and genes) are compared to fraternal twins reared together (who also share family environment but only share half their genes). Another condition that permits the disassociation of genes and environment is adoption. In one kind of adoption study, biological siblings reared together (who share the same family environment and half their genes) are compared to adoptive siblings (who share their family environment but none of their genes).

In many cases, it has been found that genes make a substantial contribution, including psychological traits such as intelligence and personality.[32] Yet heritability may differ in other circumstances, for instance environmental deprivation. Examples of low, medium, and high heritability traits include:

Low heritabilityMedium heritabilityHigh heritability
Specific languageWeightBlood type
Specific religionReligiosityEye color

Twin and adoption studies have their methodological limits. For example, both are limited to the range of environments and genes which they sample. Almost all of these studies are conducted in Western, first-world countries, and therefore cannot be extrapolated globally to include poorer, non-western populations. Additionally, both types of studies depend on particular assumptions, such as the equal environments assumption in the case of twin studies, and the lack of pre-adoptive effects in the case of adoption studies.

Since the definition of "nature" in this context is tied to "heritability", the definition of "nurture" has necessarily become very wide, including any type of causality that is not heritable. The term has thus moved away from its original connotation of "cultural influences" to include all effects of the environment, including; indeed, a substantial source of environmental input to human nature may arise from stochastic variations in prenatal development and is thus in no sense of the term "cultural".[33][34]

Interaction of genes and environment[edit]

Main article: Gene–environment interaction

Many properties of the brain are genetically organized, and don't depend on information coming in from the senses.
— Steven Pinker

Heritability refers to the origins of differences between people. Individual development, even of highly heritable traits, such as eye color, depends on a range of environmental factors, from the other genes in the organism, to physical variables such as temperature, oxygen levels etc. during its development or ontogenesis.

The variability of trait can be meaningfully spoken of as being due in certain proportions to genetic differences ("nature"), or environments ("nurture"). For highly penetrantMendelian genetic disorders such as Huntington's disease virtually all the incidence of the disease is due to genetic differences. Huntington's animal models live much longer or shorter lives depending on how they are cared for[citation needed].

At the other extreme, traits such as native language are environmentally determined: linguists have found that any child (if capable of learning a language at all) can learn any human language with equal facility.[35] With virtually all biological and psychological traits, however, genes and environment work in concert, communicating back and forth to create the individual.

At a molecular level, genes interact with signals from other genes and from the environment. While there are many thousands of single-gene-locus traits, so-called complex traits are due to the additive effects of many (often hundreds) of small gene effects. A good example of this is height, where variance appears to be spread across many hundreds of loci.[36]

Extreme genetic or environmental conditions can predominate in rare circumstances—if a child is born mute due to a genetic mutation, it will not learn to speak any language regardless of the environment; similarly, someone who is practically certain to eventually develop Huntington's disease according to their genotype may die in an unrelated accident (an environmental event) long before the disease will manifest itself.

Steven Pinker likewise described several examples:[37][38]

concrete behavioral traits that patently depend on content provided by the home or culture—which language one speaks, which religion one practices, which political party one supports—are not heritable at all. But traits that reflect the underlying talents and temperaments—how proficient with language a person is, how religious, how liberal or conservative—are partially heritable.

When traits are determined by a complex interaction of genotype and environment it is possible to measure the heritability of a trait within a population. However, many non-scientists who encounter a report of a trait having a certain percentage heritability imagine non-interactional, additive contributions of genes and environment to the trait. As an analogy, some laypeople may think of the degree of a trait being made up of two "buckets," genes and environment, each able to hold a certain capacity of the trait. But even for intermediate heritabilities, a trait is always shaped by both genetic dispositions and the environments in which people develop, merely with greater and lesser plasticities associated with these heritability measures.

Heritability measures always refer to the degree of variation between individuals in a population. That is, as these statistics cannot be applied at the level of the individual, it would be incorrect to say that while the heritability index of personality is about 0.6, 60% of one's personality is obtained from one's parents and 40% from the environment. To help to understand this, imagine that all humans were genetic clones. The heritability index for all traits would be zero (all variability between clonal individuals must be due to environmental factors). And, contrary to erroneous interpretations of the heritability index, as societies become more egalitarian (everyone has more similar experiences) the heritability index goes up (as environments become more similar, variability between individuals is due more to genetic factors).

One should also take into account the fact that the variables of heritability and environmentality are not precise and vary within a chosen population and across cultures. It would be more accurate to state that the degree of heritability and environmentality is measured in its reference to a particular phenotype in a chosen group of a population in a given period of time. The accuracy of the calculations is further hindered by the number of coefficients taken into consideration, age being one such variable. The display of the influence of heritability and environmentality differs drastically across age groups: the older the studied age is, the more noticeable the heritability factor becomes, the younger the test subjects are, the more likely it is to show signs of strong influence of the environmental factors.

Some have pointed out that environmental inputs affect the expression of genes[16] (see the article on epigenetics). This is one explanation of how environment can influence the extent to which a genetic disposition will actually manifest.[citation needed] The interactions of genes with environment, called gene–environment interactions, are another component of the nature–nurture debate. A classic example of gene–environment interaction is the ability of a diet low in the amino acid phenylalanine to partially suppress the genetic disease phenylketonuria. Yet another complication to the nature–nurture debate is the existence of gene-environment correlations. These correlations indicate that individuals with certain genotypes are more likely to find themselves in certain environments. Thus, it appears that genes can shape (the selection or creation of) environments. Even using experiments like those described above, it can be very difficult to determine convincingly the relative contribution of genes and environment.

A study conducted by T.J. Bouchard, Jr. showed data that has been evidence for the importance of genes when testing middle-aged twins reared together and reared apart. The results shown have been important evidence against the importance of environment when determining, happiness, for example. In the Minnesota study of twins reared apart, it was actually found that there was higher correlation for monozygotic twins reared apart (0.52)than monozygotic twins reared together (0.44). Also, highlighting the importance of genes, these correlations found much higher correlation among monozygotic than dizygotic twins that had a correlation of 0.08 when reared together and −0.02 when reared apart.[39]

Social pre-wiring[edit]

The social pre-wiring hypothesis refers to the ontogeny of social interaction. Also informally referred to as, "wired to be social." The theory questions whether there is a propensity to socially oriented action already present before birth. Research in the theory concludes that newborns are born into the world with a unique genetic wiring to be social[40].

Circumstantial evidence supporting the social pre-wiring hypothesis can be revealed when examining newborns' behavior. Newborns, not even hours after birth, have been found to display a preparedness for social interaction. This preparedness is expressed in ways such as their imitation of facial gestures. This observed behavior cannot be contributed to any current form of socialization or social construction. Rather, newborns most likely inherit to some extent social behavior and identity through genetics[40].

Principal evidence of this theory is uncovered by examining Twin pregnancies. The main argument is, if there are social behaviors that are inherited and developed before birth, then one should expect twin foetuses to engage in some form of social interaction before they are born. Thus, ten foetuses were analyzed over a period of time using ultrasound techniques. Using kinematic analysis, the results of the experiment were that the twin foetuses would interact with each other for longer periods and more often as the pregnancies went on. Researchers were able to conclude that the performance of movements between the co-twins were not accidental but specifically aimed[40].

The social pre-wiring hypothesis was proved correct, "The central advance of this study is the demonstration that 'social actions' are already performed in the second trimester of gestation. Starting from the 14th week of gestation twin foetuses plan and execute movements specifically aimed at the co-twin. These findings force us to predate the emergence of social behavior: when the context enables it, as in the case of twin foetuses, other-directed actions are not only possible but predominant over self-directed actions."[40].

Obligate vs. facultative adaptations[edit]

Traits may be considered to be adaptations (such as the umbilical cord), byproducts of adaptations (the belly button) or due to random variation (convex or concave belly button shape).[41] An alternative to contrasting nature and nurture focuses on "obligate vs. facultative" adaptations.[41] Adaptations may be generally more obligate (robust in the face of typical environmental variation) or more facultative (sensitive to typical environmental variation). For example, the rewarding sweet taste of sugar and the pain of bodily injury are obligate psychological adaptations—typical environmental variability during development does not much affect their operation.[42] On the other hand, facultative adaptations are somewhat like "if-then" statements.[43] An example of a facultative psychological adaptation may be adult attachment style. The attachment style of adults, (for example, a "secure attachment style," the propensity to develop close, trusting bonds with others) is proposed to be conditional on whether an individual's early childhood caregivers could be trusted to provide reliable assistance and attention. An example of a facultative physiological adaptation is tanning of skin on exposure to sunlight (to prevent skin damage).

Advanced techniques[edit]

Quantitative studies of heritable traits throw light on the question.

Developmental genetic analysis examines the effects of genes over the course of a human lifespan. Early studies of intelligence, which mostly examined young children, found that heritability measured 40–50%. Subsequent developmental genetic analyses found that variance attributable to additive environmental effects is less apparent in older individuals,[44][45][46] with estimated heritability of IQ increasing in adulthood.

Multivariate genetic analysis examines the genetic contribution to several traits that vary together. For example, multivariate genetic analysis has demonstrated that the genetic determinants of all specific cognitive abilities (e.g., memory, spatial reasoning, processing speed) overlap greatly, such that the genes associated with any specific cognitive ability will affect all others. Similarly, multivariate genetic analysis has found that genes that affect scholastic achievement completely overlap with the genes that affect cognitive ability.

Extremes analysis examines the link between normal and pathological traits. For example, it is hypothesized that a given behavioral disorder may represent an extreme of a continuous distribution of a normal behavior and hence an extreme of a continuous distribution of genetic and environmental variation. Depression, phobias, and reading disabilities have been examined in this context.

For a few highly heritable traits, studies have identified loci associated with variance in that trait, for instance in some individuals with schizophrenia.[47]

Entrepreneurship[edit]

Through studies of identical twins separated at birth, one-third of their creative thinking abilities come from genetics and two-thirds come from learning.[48] Research suggests that between 37 and 42 percent of the explained variance can be attributed to genetic factors.[49] The learning primarily comes in the form of human capital transfers of entrepreneurial skills through parental role modeling.[50] Other findings agree that the key to innovative entrepreneurial success comes from environmental factors and working “10,000 hours” to gain mastery in entrepreneurial skills.[51]

Heritability of intelligence[edit]

Main article: Heritability of IQ

Evidence from behavioral genetic research suggests that family environmental factors may have an effect upon childhood IQ, accounting for up to a quarter of the variance. The American Psychological Association's report "Intelligence: Knowns and Unknowns" (1995) states that there is no doubt that normal child development requires a certain minimum level of responsible care. Here, environment is playing a role in what is believed to be fully genetic (intelligence) but it was found that severely deprived, neglectful, or abusive environments have highly negative effects on many aspects of children's intellect development. Beyond that minimum, however, the role of family experience is in serious dispute. On the other hand, by late adolescence this correlation disappears, such that adoptive siblings no longer have similar IQ scores.[52]

Moreover, adoption studies indicate that, by adulthood, adoptive siblings are no more similar in IQ than strangers (IQ correlation near zero), while full siblings show an IQ correlation of 0.6. Twin studies reinforce this pattern: monozygotic (identical) twins raised separately are highly similar in IQ (0.74), more so than dizygotic (fraternal) twins raised together (0.6) and much more than adoptive siblings (~0.0).[53] Recent adoption studies also found that supportive parents can have a positive effect on the development of their children.[54]

Personality traits[edit]

Main article: Personality psychology § Genetic basis of personality

Personality is a frequently cited example of a heritable trait that has been studied in twins and adoptees using behavioral genetic study designs. The most famous categorical organization of heritable personality traits were created by Goldberg (1990) in which he had college students rate their personalities on 1400 dimensions to begin, and then narrowed these down into "The Big Five" factors of personality—Openness, conscientiousness, extraversion, agreeableness, and neuroticism. The close genetic relationship between positive personality traits and, for example, our happiness traits are the mirror images of comorbidity in psychopathology. These personality factors were consistent across cultures, and many studies have also tested the heritability of these traits.

Identical twins reared apart are far more similar in personality than randomly selected pairs of people. Likewise, identical twins are more similar than fraternal twins. Also, biological siblings are more similar in personality than adoptive siblings. Each observation suggests that personality is heritable to a certain extent. A supporting article had focused on the heritability of personality (which is estimated to be around 50% for subjective well-being) in which a study was conducted using a representative sample of 973 twin pairs to test the heritable differences in subjective well-being which were found to be fully accounted for by the genetic model of the Five-Factor Model’s personality domains.[55] However, these same study designs allow for the examination of environment as well as genes.

Adoption studies also directly measure the strength of shared family effects. Adopted siblings share only family environment. Most adoption studies indicate that by adulthood the personalities of adopted siblings are little or no more similar than random pairs of strangers. This would mean that shared family effects on personality are zero by adulthood.

In the case of personality traits, non-shared environmental effects are often found to out-weigh shared environmental effects. That is, environmental effects that are typically thought to be life-shaping (such as family life) may have less of an impact than non-shared effects, which are harder to identify. One possible source of non-shared effects is the environment of pre-natal development. Random variations in the genetic program of development may be a substantial source of non-shared environment. These results suggest that "nurture" may not be the predominant factor in "environment". Environment and our situations, do in fact impact our lives, but not the way in which we would typically react to these environmental factors. We are preset with personality traits that are the basis for how we would react to situations. An example would be how extraverted prisoners become less happy than introverted prisoners and would react to their incarceration more negatively due to their preset extraverted personality.[31]:Ch 19 Behavioral genes are somewhat proven to exist when we take a look at fraternal twins. When fraternal twins are reared apart, they show the same similarities in behavior and response as if they have been reared together.[56]

Genetics[edit]

Genomics[edit]

Main article: Genomics

The relationship between personality and people's own well-being is influenced and mediated by genes (Weiss, Bates, & Luciano, 2008). There has been found to be a stable set point for happiness that is characteristic of the individual (largely determined by the individual's genes). Happiness fluctuates around that setpoint (again, genetically determined) based on whether good things or bad things are happening to us ("nurture"), but only fluctuates in small magnitude in a normal human. The midpoint of these fluctuations is determined by the "great genetic lottery" that people are born with, which leads them to conclude that how happy they may feel at the moment or over time is simply due to the luck of the draw, or gene. This fluctuation was also not due to educational attainment, which only accounted for less than 2% of the variance in well-being for women, and less than 1% of the variance for men.[39]

They consider that the individualities measured together with personality tests remain steady throughout an individual’s lifespan. They further believe that human beings may refine their forms or personality but can never change them entirely. Darwin's Theory of Evolution steered naturalists such as George Williams and William Hamilton to the concept of personality evolution. They suggested that physical organs and also personality is a product of natural selection.[57]

With the advent of genomic sequencing, it has become possible to search for and identify specific gene polymorphisms that affect traits such as IQ and personality. These techniques work by tracking the association of differences in a trait of interest with differences in specific molecular markers or functional variants. An example of a visible human trait for which the precise genetic basis of differences are relatively well known is eye color. For traits with many genes affecting the outcome, a smaller portion of the variance is currently understood: For instance for height known gene variants account for around 5–10% of height variance at present.[citation needed] When discussing the significant role of genetic heritability in relation to one's level of happiness, it has been found that from 44% to 52% of the variance in one's well-being is associated with genetic variation. Based on the retest of smaller samples of twins studies after 4,5, and 10 years, it is estimated that the heritability of the genetic stable component of subjective well-being approaches 80%.[39] Other studies that have found that genes are a large influence in the variance found in happiness measures, exactly around 35–50%.[58][59][60][61]

In contrast to views developed in 60's that gender identity is primarily learned (which led to policy-based surgical sex changed in children such as David Reimer), genomics has provided solid evidence that both sex and gender identities are primarily influenced by genes:

It is now clear that genes are vastly more influential than virtually any other force in shaping sex identity and gender identity…[T]he growing consensus in medicine is that…children should be assigned to their chromosomal (i.e., genetic) sex regardless of anatomical variations and differences—with the option of switching, if desired, later in life.

— Siddhartha Mukherjee, The Gene: An Intimate History

Linkage and association studies[edit]

In their attempts to locate the genes responsible for configuring certain phenotypes, researches resort to two different techniques. Linkage study facilitates the process of determining a specific location in which a gene of interested is located. This methodology is applied only among individuals that are related and does not serve to pinpoint specific genes. It does, however, narrow down the area of search, making it easier to locate one or several genes in the genome which constitute a specific trait.

Association studies, on the other hand, are more hypothetic and seek to verify whether a particular genetic variable really influences the phenotype of interest. In association studies it is more common to use case-control approach, comparing the subject with relatively higher or lower hereditary determinants with the control subject.

See also[edit]

References[edit]

  1. ^In English at least since Shakespeare (The Tempest 4.1: a born devil, on whose nature nurture can never stick) and Richard Barnfield (Nature and nurture once together met / The soule and shape in decent order set.); in the 18th century used by Philip Yorke, 1st Earl of Hardwicke (Roach v. Garvan, "I appointed therefore the mother guardian, who is properly so by nature and nurture, where there is no testamentary guardian.")
  2. ^English usage is based on a tradition going back to medieval literature, where the opposition of nature ("instinct, inclination") norreture ("culture, adopted mores") is a common motif, famously in Chretien de Troyes' Perceval, where the hero's effort to suppress his natural impulse of compassion in favor of what he considers proper courtly behavior leads to catastrophe. Lacy, Norris J. (1980) The Craft of Chrétien de Troyes: An Essay on Narrative Art, Brill Archive, p. 5.
  3. ^in Plato's Protagoras 351b; an opposition is made by Protagoras' character between art on one hand and constitution and fit nurture (nature and nurture) of the soul on the other, art (as well as rage and madness; ἀπὸ τέχνης ἀπὸ θυμοῦ γε καὶ ἀπὸ μανίας) contributing to boldness (θάρσος), but nature and nurture combine to contribute to courage (ἀνδρεία). "Protagoras, in spite of the misgiving of Socrates, has no scruple in announcing himself a teacher of virtue, because virtue in the sense by him understood seems sufficiently secured by nature and nurture." Mackay, R. W. (1869) "Introduction to the Meno in comparison with the Protagoras" p. 138 in Meno: A Dialogue on the Nature and Meaning of Education.
  4. ^"Nature Nurture in Psychology | Simply Psychology". simplypsychology.org. Retrieved 2017-05-04. 
  5. ^Proceedings, Volume 7. Royal Institution of Great Britain. 1875. 
  6. ^Francis Galton (1895). English Men of Science: Their Nature and Nurture. D. Appleton. 
  7. ^David Moore (2003). The Dependent Gene: The Fallacy of "Nature Vs. Nurture". Henry Holt and Company. ISBN 9780805072808. 
  8. ^Moore, David S. (2003). The Dependent Gene: The Fallacy of Nature Vs. Nurture, Henry Holt. ISBN 978-0805072808
  9. ^Esposito, E. A., Grigorenko, E.L., & Sternberg, R. J. (2011). "The Nature-Nurture Issue (an Illustration Using Behaviour-Genetic Research on Cognitive Development)". In Alan Slater, & Gavin Bremner (eds.) An Introduction to Developmental Psychology: Second Edition, BPS Blackwell.:85
  10. ^Dusheck, Jennie (October 2002), The Interpretation of Genes. Natural History
  11. ^Carlson, N.R. et al.. (2005) Psychology: the science of behaviour (3rd Canadian ed) Pearson. ISBN 0-205-45769-X
  12. ^Ridley, M. (2003) Nature via Nurture: Genes, Experience, & What Makes Us Human. Harper Collins. ISBN 0-00-200663-4
  13. ^Westen, D. (2002) Psychology: Brain, Behavior & Culture. Wiley & Sons. ISBN 0-471-38754-1
  14. ^Powledge, Tabitha M. (August 2011). "Behavioral Epigenetics: How Nurture Shapes Nature". BioScience. 61 (8): 588–592. doi:10.1525/bio.2011.61.8.4. 
  15. ^Normile, Dennis (February 2016). "Nature From Nurture". Science. 351 (6276): 908–910. doi:10.1126/science.351.6276.908. (Subscription required (help)). 
  16. ^ abMoore, David S. (2015). The Developing Genome: An Introduction to Behavioral Epigenetics (1st ed.). Oxford University Press. ISBN 9780199922345. 
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This chart illustrates three patterns one might see when studying the influence of genes and environment on traits in individuals. Trait A shows a high sibling correlation, but little heritability (i.e. high shared environmental variance c2; low heritability h2). Trait B shows a high heritability since correlation of trait rises sharply with degree of genetic similarity. Trait C shows low heritability, but also low correlations generally; this means Trait C has a high nonshared environmental variance e2. In other words, the degree to which individuals display Trait C has little to do with either genes or broadly predictable environmental factors—roughly, the outcome approaches random for an individual. Notice also that even identical twins raised in a common family rarely show 100% trait correlation.
The "two buckets" view of heritability.
More realistic "homogenous mudpie" view of heritability.

Perceptions of nature, nurture and behaviour

Department of Politics, Philosophy and Religious Studies, Lancaster University, County South, Lancaster, LA1 4YL UK

Mairi Levitt, Email: ku.ca.retsacnal@ttivel.m.

Corresponding author.

Author information ►Article notes ►Copyright and License information ►

Received 2013 Sep 18; Accepted 2013 Dec 6.

Copyright © Levitt; licensee Springer. 2013

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Trying to separate out nature and nurture as explanations for behaviour, as in classic genetic studies of twins and families, is now said to be both impossible and unproductive. In practice the nature-nurture model persists as a way of framing discussion on the causes of behaviour in genetic research papers, as well as in the media and lay debate. Social and environmental theories of crime have been dominant in criminology and in public policy while biological theories have been seen as outdated and discredited. Recently, research into genetic variations associated with aggressive and antisocial behaviour has received more attention in the media. This paper explores ideas on the role of nature and nurture in violent and antisocial behaviour through interviews and open-ended questionnaires among lay publics. There was general agreement that everybody’s behaviour is influenced to varying degrees by both genetic and environmental factors but deterministic accounts of causation, except in exceptional circumstances, were rejected. Only an emphasis on nature was seen as dangerous in its consequences, for society and for individuals themselves. Whereas academic researchers approach the debate from their disciplinary perspectives which may or may not engage with practical and policy issues, the key issue for the public was what sort of explanations of behaviour will lead to the best outcomes for all concerned.

Keywords: Nature and nurture, Genes and environment, Genes and crime, Behavioural genetics

Perceptions of nature, nurture and behaviour

Trying to separate out nature and nurture as explanations for behaviour, as in classic genetic studies of twins and families, is now said to be both impossible and unproductive. The nature-nurture debate is declared to be officially redundant by social scientists and scientists, ‘outdated, naive and unhelpful’ (Craddock, 2011, p.637), ‘a false dichotomy’ (Traynor 2010, p.196). Geneticists argue that nature and nurture interact to affect behaviour through complex and not yet fully understood ways, but, in practice, the debate continues1. Research papers by psychologists and geneticists still use the terms nature and nurture, or genes and environment, to consider their relative influences on, for example, temperament and personality, childhood obesity and toddler sleep patterns (McCrae et al., 2000; Anderson et al., 2007; Brescianini, 2011). These papers separate out and quantify the relative influences of nature/genes and nurture/environment. These papers might be taken to indicate how individuals acquire their personality traits or toddlers acquire their sleep patterns; part is innate or there at birth and part is acquired after birth due to environmental influences. The findings actually refer to technical heritability which is, ‘the proportion of phenotypic variation attributable to genetic differences between individuals’ (Keller, 2010, p.57). In practice, as Keller illustrates, there is ‘slippage’ between heritability, meaning a trait being biologically transmissible, and technical heritability. This is not simply a mistake made by the media or ‘media hype’ but is, she argues, ‘almost impossible to avoid’ (ibid, p.71).

While researchers are aware of the complexity of gene-environment interaction, the ‘nature and nurture’ model persists as a simple way of framing discussion on the causes of behaviours. It is also a site of struggle between (and within) academic disciplines and, through influence on policy, has consequences for those whose behaviours are investigated. There is general agreement between social scientists and geneticists about the past abuses of genetics but disagreement over whether it will be possible for the new behavioural genetics to avoid discrimination and eugenic practices, and about the likely benefits that society will gain from this research (Parens et al. 2006, xxi). In a special issue of the American Journal of Sociology ‘Exploring genetics and social structure’, Bearman considers the reasons why sociologists are concerned about genetic effects on behaviour; first they see it as legitimating existing societal arrangements, which assumes that ‘genetic’ is unchangeable. Second, if sociologists draw on genetic research it contaminates the sociological enterprise and, third, whatever claims are made to the contrary, it is a eugenicist project (Bearman, 2008, vi). As we will see all these concerns were expressed by the publics in this study. Policy makers and publics are interested in explaining problem behaviour in order to change/control it, not in respecting disciplinary boundaries, and will expect the role of genetics to be considered alongside social factors.2

Social and environmental theories of criminal behaviour have been dominant in criminology, and in public policy (Walsh, 2009, p.7). Genetic disorders and mental illness have provided explanations for a small minority of offenders with specific conditions. A 2007 survey of American criminologists found that ‘criminologists of all ideological persuasions view alleged biosocial causes of crime (hormonal, genetic, and evolutionary factors and possibly low intelligence) as relatively unimportant’ compared with environmental causes (Cooper et al., 2010). Sociology textbooks have typically discussed biological theories of criminality only as discredited (Haralambos and Holborn, 2004, Giddens, 2009). Biosocial theories are seen as attractive to ‘agents of social control’ and to be more likely to lead to abusive treatment of offenders. However, with increasing research and public interest in genetics more attention has been paid to biological aspects of crime and to genetic variations within the normal range. Research has focussed on violent and antisocial behaviours which are criminal or may be seen as a precursor to criminal behaviour, for example, antisocial behaviour in young people. Media reports have headlined ‘warrior genes’, ‘the aggressive gene’ and the ‘get out of jail free gene’, all referring to levels of monoamine oxidase A (MAOA) (Lea and Chambers, 2007; Levitt and Pieri, 2009)3. Think tanks and ethics groups have considered the ethics and practicalities of genetic testing for behavioural traits (Campbell and Ross, 2004; Dixon, 2005 Nuffield Council on Bioethics, 2002).

An attraction of research into genes and behaviour is the hope that identifying a genetic factor that is correlated with an increased incidence of, say, violent and antisocial behaviour, will point to a way of reducing such behaviour. Fotaki discusses the attraction of biological explanations of inequalities in health based on the assumption that genetic interventions ‘would succeed in addressing the causes of ill health that public health policies cannot.’ (Fotaki, 2011, p.641). The danger is that biological explanations ‘are once more employed for political purposes to explain away the social roots of health inequalities.’ (ibid). Social scientists, and criminologists, have presented biological/genetic explanations of behaviour as dangerous in terms of their potential effect on the individuals or groups identified as genetically at risk. There are obvious dangers of discrimination against, and the stigmatisation of, already vulnerable groups who would be the first to be tested i.e. ‘problem’ families or minority ethnic groups. Discrimination could affect education, employment and family life. The effect of an individual being told s/he has a risk based on a genetic test has been much discussed in relation to health risks (Claassen et al., 2010. While such information could be motivating, because it is personalised, it can also induce a fatalistic attitude that discourages the person from taking preventative measures. Claasen et al. conclude that it is important to identify those vulnerable to the fatalistic impact and to tailor health risk information (ibid p.194). Identifying risk for behaviour, rather than for disease, is likely to be more problematic because of the difficulty of finding preventative measures that are within the individuals’ own control.

..using DNA to assess risk, make a diagnosis or tailor treatments, may weaken beliefs in the efficacy of preventive behaviour and reinforce biological ways of reducing risk, resulting in a preference for medication as opposed to behavioural means to control or reduce risk (ibid, xiv).

Claasen et al.’s comment on genetic tests for health conditions could apply equally to parents given a behavioural risk for their young child from a genetic test, perhaps before any problem behaviour was evident. The test result could weaken parents’ belief that they could take action to prevent/reduce the risk of the behaviour developing in their child and pharmaceutical solutions, as posited by Caspi et al. might not be available (Caspi et al., 2002, xvii). However, it is not necessarily the case that evidence of genetic or biological influence on behaviour leads to more punitive treatment. DeLisi et al. give the example of the use of findings from adolescent brain science in the case of Roper v. Simmons in the US which abolished the death penalty for adolescents. On the basis of the research it was stated that young people under the age of 18 ‘are more vulnerable or susceptible to negative influences and outside pressures including peer pressure’ (DeLisa et al., 2010, p.25) When evidence on genetic traits associated with criminal behaviour has been allowed by courts, mainly in the US, it has so far more often been accepted as a mitigating rather than an aggravating factor in the offenders’ behaviour (Denno, 2009, Farahany and Coleman, 2006).

Environmental explanations of behaviour can, of course, also be presented as deterministic, claiming a closed future for those experiencing poverty and disadvantage. However, it is biological explanations that have caused more concern not only because of the history of eugenics but also because they may be seen as more fundamental, being there from birth, and as harder to change. The public in surveys are reported to see the greatest role for genetic factors in physical features, a lesser role in health conditions and a smaller role still in human behaviour (Condit, 2010, p.619).

Public perceptions

The model of nature/genes and nurture/environment is still used in behavioural genetics, as well as in popular culture, and has implications for public policy, including the treatment of offenders who claim that a genetic trait has influenced their criminal behaviour. The aim of this research was to explore ideas on the causes of behaviour, particularly violent and antisocial behaviour and examine how respondents use the nature/nurture model. This qualitative research looks at the ways in which lay publics in different age groups conceptualise the factors and influences that made them who they are and their explanations for the behaviour of other people; especially violent behaviour. It was hypothesised that the increased research and media emphasis on the role of genetic factors in health and behaviour might result in an increasing interest in ‘nature’, biology and genes as explanations for behaviour particularly among the young, but, when explaining their own behaviour people might prefer to see themselves as agents with control over their lives. By exploring explanations of behaviour with respondents from different generations, age differences should be apparent.

The views of 78 respondents from 3 generations were gathered by individual interview and questionnaires, using the same open ended questions and responses to two real-life criminal court case studies where environmental or genetic factors had been used by the defence team. Respondents were drawn from a group of retired people participating in an informal ‘senior learners’ programme at Lancaster University, a group of their mainly younger relatives and, in order to recruit more third generation respondents, a group of first year students taking a criminology module. The senior learners group had a programme of talks and discussions and could attend undergraduate lectures. They had, by definition, shown an interest in current issues in a range of fields. There were no educational or age requirements for the group but all the volunteers were retired from paid work and were aged from around 65 years to over 80 years.. They had had similar careers to those popular with social science students; social work, probation, teaching and administrative positions. The senior learners were asked to pass on questionnaires to younger relatives to investigate age differences in attitudes. The first 13 senior learners who responded were interviewed but as only 15 questionnaires were received from their relatives ethical approval was obtained to distribute the same questionnaire to Lancaster University students taking the criminology first year module. Most students were enrolled on social science degrees, including psychology and sociology, and age 18 or 19. While the sample of senior learners and relatives had only a few more women than men, 78 per cent of the students were female reflecting the gender balance on the module as a whole. This makes it difficult to comment on any gender differences in responses. No claims to generalisability are made for this exploratory study. Responses were coded and entered on SPSS and also analysed thematically using Atlas-ti.

The introduction to the interviews and questionnaire was ‘I am interested in your views and ideas on what makes us the people we are; what makes people behave the way they do? What is the influence of nature and nurture?’ The terms, nature and nurture were not used again until the final question. Although the terms were not defined all respondents readily used them with consistent meanings. They identified ‘nature’ with biology, ‘what you are born with’ and genes or DNA and nurture with all aspects of the environment including parenting, socio-economic conditions, the food you eat, culture and other people. Their understanding of environment was therefore similar to that used by genetic researchers; environment as everything that is external to the individual, although they tended to refer more to the social than the biological environment.

A general warm-up question asked whether, in their own family, there was anything they thought of as a ‘family trait’. Then respondents were asked; ‘Imagine a baby swapped at birth and brought up in a completely different family– which influences do you think would be most important – the influence of the birth parents or the influences of the new family- and why?’4 The rest of the interview schedule, and the subsequent questionnaire, consisted of open-ended questions.

Respondents were asked how they would explain different kinds of behaviour if they came across a child who is kind and considerate; a young person who displays antisocial and aggressive behaviour adult and an adult with criminal convictions for violence. This was to tap into any differences in general explanations of good and bad behaviour in young people and adults. A quotation about the child killers in the Bulger case being ‘unreformable’ was used to ascertain whether they saw some types of violent behavior, and the actors concerned, as immutable. In order to see how respondents conceptualized the influences of nature/biology/genes and environment/people/experiences in their own lives, respondents were asked to write down ‘what or who made you what you are today’ and any explanation of their responses. Comments were gathered on the introduction of an environmental factor (childhood neglect) by the defence in a violent attack by two young boys in England, and on a genetic factor (MAOA levels) introduced by the defence in an criminal court in Italy. Respondents were asked how they thought such evidence should be dealt with; whether it should affect the degree of blame and whether it should affect criminal responsibility. The final question asked if it mattered ‘for individuals or society’ whether nature or nurture was seen as most important in explaining problem behaviour. Those interviewed were asked if they had any further comments and there was a space for any additional comments on the questionnaire.

This paper focuses on the ways in which respondents employed nature/genes and nurture/environment in their responses as a whole and what other concepts they drew on when explaining behaviour.

Respondents’ explanations of what makes people behave the way they do are discussed through three themes.

  1. Nurture is more influential than nature

  2. Nature and nurture interact

  3. Emphasising nature (but never nurture) can be dangerous

Theme 1: Nurture is more influential than nature

Whether asked about influences on a baby adopted at birth, on their own lives, on an aggressive child or a violent young person, almost all respondents emphasised nurture. Parents and family were seen as the most important influences for babies and young children, moving to peer group and other relationships and experiences for a young person. The explanation for the violent behaviour of an adult had more to do with the individual and the importance of nurture/environment in explaining behaviour weakened. The quotations below explaining behaviour in a child adopted at birth, a young person and an adult illustrate the widening of influences from infancy through childhood and the onus on adults to take responsibility for themselves.

[a child] The environment in which a child grows up in, particularly the influence and role of the parents shapes how a child will grow up and what sort of adult they will be (77 Student).

[a young person] I believe that upbringing shapes a person’s personality. Provisions of education, lifestyle opportunities and friendship groups all determine ….outlook. You can see evidence in young people at the school I teach at (20 Relative).

Once adult they have to take responsibility for themselves and address whatever has been in their background. An adult can’t turn round and say it’s not my fault (5 Senior Learner).

Participants also saw themselves as shaped by the people surrounding them, starting with their parents, or those who brought them up. Several mentioned the illness and/or death of a parent during their childhood and older respondents talked about separation due to the second world war. Students were especially likely to mention the influence of morals instilled in them by their parents, the core values and discipline that they were taught at home. Educational experiences were important to all. For the senior learners the school leaving age had been age 15, so whether or not they stayed on at school and took public examinations was crucial for their future, and, this decision depended largely on their parents and environment. For the student respondents who had come to university from school, life so far has been ‘kind of set-out’ (41 Student), in the sense that they had progressed through the education system to gain qualifications for university. For their peer group it was normal still to be in education or training at the age of 18.

The lasting effects of early influences were particularly striking among the senior learners, because they were much further removed in years from their childhood. Many related stories about parental influence and also about teachers who taught them at least 50 years ago and had affected them for better or worse. For example a senior learner recalled one of her teachers;

I hated primary school – the teacher in 3rd or 4th year juniors [for ages 9–11] I hated her she was not a nice woman….. I passed to go to the grammar school and it shocked her. She made a derogatory comment – may not have been directed at me but felt it was- about some who should have passed and didn’t and some passing who should not have done…… I always vowed I would never be like that when I was teaching….(11 Senior Learner).

Those who related negative influences presented themselves as active in response, not necessarily at the time but later in their lives. For example a student whose mother had died wrote that ‘it made me more independent’ and another student who was bullied at school wrote that ‘it made me stronger’. The adult had to deal with all the influences (negative or positive) and take control.

Theme 2: Nature and nurture interact

While respondents’ view of themselves and of a child adopted at birth assigned greater influence to environment this did not mean that they held a simplistic model of, for example 60:40 nurture to nature. In this one question when they were asked to choose one or other as the major influence, almost all chose nurture, as many social scientists might do. However, in open questions and comments more complex interactive models were expressed. Environment/nurture can affect genes/nature and vice versa. No one used the term epigenetics but responses referred to the possibility of environmental influences affecting gene expression, for example;

People with certain predispositions (e.g. to violence) are affected by society, and society affects how their genes are expressed (40 Student).

An older respondent reflects on personal experience of child rearing and asks whether nurture is influenced by nature;

I think the nature nurture debate is very interesting. In my family I can see where my children have their own natures that have developed despite being brought up in the same family with the same boundaries etc. However, as a parent did I alter how I nurture them to take into account their nature? (14 Senior Learner).

This quotation illustrates the inseparability of nature and nurture. The child is developing within the family and the parent is developing parenting strategies informed by previous experiences and by other influences including the reactions of the children.

It was obvious to respondents that both genetic and environmental factors impact on everyone (although the role of genes is not yet understood) and it will be harder for some than for others to behave well because of their genes and environment. These people may need different treatment or extra help if they have committed violent and aggressive crimes but that does not excuse their behaviour. Only in exceptional cases, like insanity, can a young person or adult be said to have no choice but to act in a particular way. It is important that people are seen as responsible while also giving them the help they need. In these two comments the treatment for environmental problems and ‘biology’ are similar; the individual can be helped to modify his/her behaviour.

No, [nature and nurture] both play a part, but they can’t be the explanation for everything. Some people grow up in broken homes and get treated appallingly- yet they seem to understand right + wrong and accept responsibility for their actions. There are too many excuses and we never solve any problems, just make them harder to resolve.......I think if you are sane and you know right from wrong you need to suffer the consequences if you’ve committed a crime, but I do appreciate you may need help psychologically if you have anger issues, for example. If we constantly find reasons to diminish blame from people who have committed heinous acts of crime more people will think they can get away with it and it will cause more harm than good (78 Student).

Some say you can’t fight your biology, but there are social factors that can stop bad behaviour like learned restraint (72 Student).

The desire to leave a space for individual agency may be linked to the finding that emphasising nature, but never nurture, could be dangerous. It is clear that as children grow up they can exercise more control over their environment, although some have more control and choices than others. On the other hand, whatever the individual is born with (genes and nature) is, or seems to be, less malleable which could lead to different criminal justice policies and different social perceptions of the criminal.

Theme 3: Emphasising nature (but never nurture) can be dangerous for society as a whole as well as for the criminal and victims

The question asked was whether it mattered ‘for individuals or society’ if either nature or nurture was seen as most important in explaining problem behavior. The two most popular answers were that both nature and nurture were needed to explain behaviour, or, that nurture was more important and that there were dangers in emphasising nature. No one in the sample regarded an emphasis on nurture as dangerous or detrimental to the individual or society. On the contrary, emphasising nurture was thought more likely to lead to non-punitive treatment of offenders. There would be attempts to alter future behaviour through improved education and parenting and spreading of knowledge in society about the impact nurture has on young people. Society as a whole would share the blame rather than the individual. As a student put it; ‘society as a whole [would be] open for criticism’ (55 S). An emphasis on nurture was therefore seen as more likely to lead to understanding of problem behaviours and effective treatment, however, the individuals were still to be held responsible for their behaviour.

In contrast there was a mistrust of nature/genetic explanations that again centred on the practical consequences for individuals. It would affect the way criminals were treated by others but could also change their view of themselves. Behaviour would be seen as unchangeable, out of the control of the individual or social action. As a consequence, individual accountability might be removed. The idea that individuals must normally be held responsible for their actions was constantly emphasised (Levitt, 2013).

It does [matter] because [if nurture is emphasised] people will care, parent and look after and raise people with more care. However if it’s proven it is nature, then people may lose the will to live (60 Student).

Several SLs referred to the examination at the end of primary education (the ‘eleven plus’) when explaining why they emphasised environment/nurture rather than nature, or, in this case, innate intelligence. The ‘eleven plus’ examination was used to decide which children would be offered a place at an academically selective grammar school and was based on the idea that intelligence, and future academic achievement, could be accurately measured and predicted at the age of 10 or 11.

‘The 11+ was a nature thing. I did the 11+ − it had an effect. Saying children not going to improve or change. Very embedded in the whole idea of nature – it can’t really be true’ (8 Senior Learner).

An emphasis on nature has practical detrimental consequences for individuals. Their status is fixed, for example as ‘not academic’ or ‘born evil’ and suggests, to them and to others, that their ‘nature’ is unchangeable or very difficult to change by individual or social action.

Yes, [it matters] hugely as position of blame is dependent on whether a person chose to do what they did .....nature suggests no control (35 Student).

Those who thought an emphasis on nature meant people were irredeemable either gave that as a reason not to emphasise nature or to suggest that in fact ‘defects’ of nature could be overcome, as in this comment by a student emphasising the power of education;

Yes it is very important because it helps to understand if people are reformable (nurture) or irredeemable (nature). I believe we are determined by our education and thus with the proper help we can change. In the case of people with major biological defects, education is still a way to get over these obstacles and society should be ready to help these people (38 Student).

It might be thought that offenders themselves would embrace a genetic explanation of their behaviour if this was interpreted, as the respondents feared, as meaning they were not responsible for their crimes. However, a small study of juvenile offenders in the Netherlands found that they gave social explanations of their crimes and most rejected the idea that biology might be a factor. They committed a crime for a specific purpose like to get money or to impress others or they gave environmental reasons such as a deprived background or peer pressure or explained their offences were due to psychological conditions brought on by the use of alcohol and soft drugs (Horstkötter et al., 2012, p.291). Whether they gave goal directed or environmental reasons ‘most of them also state that they had a choice and that it was their choice to commit the crime’ (ibid p.292). As one young offender said in interview;

In the end the person makes the choice himself… The choices I have made also had a share in my past. But in the end I am the one who has made these choices (ibid).

Genes and environment

Respondents were at ease with the language of nature and nurture which was only used in the introduction to the questionnaire or interview. They readily equated genes with nature and nurture with all sorts of environmental influences. There was an acknowledgement that our understanding of environmental factors is greater than our understanding of genetics but that that would change. Older respondents were more likely to be concerned about such a change.

They're going to be doing a lot more with genetics. Influences policy profoundly and people have to be very careful. It worries me that seen to be [more determining]. The complexities don’t get looked at. If you emphasise environment it is safer from a policy point of view because given that most people don’t know what they are talking about it is safer to see the person as redeemable than to come down on the side of genetics and write people off (3 Senior Learner).

This quotation is typical in its view that nature/genes are seen as determining even though the influences on behaviour are, in reality, complex. Like the studies quoted at the beginning of the article respondents often acknowledged the complexities as nature and nurture interact but separated them when explaining the causes of specific behaviours. Students were less likely to be fearful of genetic explanations of behaviour despite their academic interest in social science. However, the hypothesis that young people might be more likely to be interested in genetic explanations for behaviour was not shown in this small study. The senior learners were more likely to refer to reading on genes and display knowledge of genetics. Older respondents and their relatives more often echoed the sociologists’ concerns about behavioural genetics discussed by Bearman earlier (Bearman, 2008). For those who feared the practical consequences of genetic explanations, like the respondent quoted above, ‘it is safer’ to keep away from them.

Some respondents in all age groups were prepared for advances in genetics to change their understanding of behaviour and prepared for current views of genes/nature as more basic, fixed and unchanging to change too. One of the youngest relatives, in her 20s, emphasised our incomplete knowledge of genetic influences on behaviour as a reason for focussing on nurture ‘at present’;

It is very tricky as we cannot see genes and I am not sure that I totally trust the idea of blaming genes for violent behaviour- maybe the person has a gene for passive behaviour as well. …….In any case we can change nurture but at present we cannot change nature so let’s do one thing at a time (20 Relative).

As respondents in this small study grappled with explanations for their own and others’ behaviour they focussed on the practical consequences leading to a greater concern over explanations based on nature than the more familiar ones based on a complex web of environmental factors. Whereas academic researchers approach the debate from their disciplinary perspectives which may or may not engage with practical and policy issues, the key issue for the public was what sort of explanations of behaviour will lead to the best outcomes for all concerned.

Endnotes

1Behavioural epigenetic research has indicated that life experiences can affect gene expression. While controversial the research suggests the possibility of further complications for the nature-nurture relationship as nurture may be said to shape nature (Buchen, 2010 Powledge, 2011). 2Bearman op cit iv. The ESRC Cambridge Network Social Contexts of Pathways into Crime (SCoPiC) promoted multidisciplinary research into the causes of crime and included the E risk longitudinal twin study led by Terri Moffitt which investigated how genetic and environmental factors shape children's disruptive behaviour http://www.scopic.ac.uk Accessed 3 Sep 2013. 3 Violent and antisocial behaviour in this longitudinal study was correlated with a common genetic trait (low expression of MAOA) only where the person was severely maltreated in childhood. Behaviour was measured on 4 outcomes; diagnoses of conduct disorder, psychological tests of aggression and anti-social personality disorder and convictions for violent crime. Caspi et al. 2002 (supplementary material). 4This initial warm-up question implied that the influences of nature and nurture could be separated and quantified as in common usage both in academic and popular discourses. As discussed respondents were able to express their views more fully (and with more complexity) in the subsequent open questions.

Acknowledgement

The support of the Economic and Social Research Council (ESRC) is gratefully acknowledged. This work was part of the Research Programme of the ESRC Genomics Network at Cesagen (ESRC Centre for Economic and Social Aspects of Genomics).

Footnotes

Competing interests

The author declares that she has no competing interests.

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