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The nature versus nurture debate concerns the relative importance of an individual's innate qualities ("nature," i.e. nativism, or innatism) versus personal experiences ("nurture," i.e. empiricism or behaviorism) in determining or causing individual differences in physical and behavioral traits. "Nature versus nurture" in its modern sense was coined by the English Victorian polymath Francis Galton in discussion of the influence of heredity and environment on social advancement, although the terms had been contrasted previously, for example by Shakespeare (in his play, The Tempest: 4.1). Galton was influenced by the book On the Origin of Species written by his cousin, Charles Darwin. The concept embodied in the phrase has been criticized for its binary simplification of two tightly interwoven parameters, as for example an environment of wealth, education and social privilege are often historically passed to genetic offspring. The view that humans acquire all or almost all their behavioral traits from "nurture" is known as tabula rasa ("blank slate"). This question was once considered to be an appropriate division of developmental influences, but since both types of factors are known to play such interacting roles in development, many modern psychologists consider the question naive—representing an outdated state of knowledge. Psychologist Donald Hebb is said to have once answered a journalist's question of "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?" That is, the idea that either nature or nurture explains a creature's behavior is a sort of single cause fallacy. In the social and political sciences, the nature versus nurture debate may be contrasted with the structure versus agency debate (i.e. socialization versus individual autonomy). For a discussion of nature versus nurture in language and other human universals, see also psychological nativism. Contents[hide]1 Scientific approach2 Heritability estimates3 Interaction of genes and environment4 IQ debate5 Personality traits 5.1 Advanced techniques6 Philosophical difficulties 6.1 Are the traits real?6.2 Biological determinism6.3 Is the problem real?7 Myths about identity8 History of the nature versus nurture debate9 See also10 References|  Scientific approach
To disentangle the effects of genes and environment, behavioral geneticists perform adoption and twin studies. Behavioral geneticists do not generally use the term "nurture" to explain that portion of the variance for a given trait (such as IQ or the Big Five personality traits) that can be attributed to environmental effects. Instead, two different types of environmental effects are distinguished: shared family factors (i.e., those shared by siblings, making them more similar) and nonshared factors (i.e., those that uniquely affect individuals, making siblings different). To express the portion of the variance due to the "nature" component, behavioral geneticists generally refer to the heritability of a trait. With regard to the Big Five personality traits as well as adult IQ in the general U.S. population, the portion of the overall variance that can be attributed to shared family effects is often negligible. On the other hand, most traits are thought to be at least partially heritable. In this context, the "nature" component of the variance is generally thought to be more important than that ascribed to the influence of family upbringing. In her Pulitzer Prize-nominated book The Nurture Assumption, author Judith Harris argues that "nurture," as traditionally defined in terms of family upbringing does not effectively explain the variance for most traits (such as adult IQ and the Big Five personality traits) in the general population of the United...