Genetics and the Environment - Nature Versus Nurture, Twin Studies, Genetic And Environmental Influenceson Intelligence, Evidence That Genes Control Speechand Language
Nature prevails enormously over nurture when the differences of nurture do not exceed what is commonly to be found among persons of the same rank of society and in the same country.
—Francis Galton, 1876
Although genetics clearly controls many of an organism's traits, it is simplistic and incorrect to assume that organisms, including humans, are completely defined by their genes. While there are some phenotypes (observable traits) that are exclusively controlled by either genetics or environment, most are influenced by a complex interaction of the two. Modern genetic study defines environment as every influence other than genetic—such as air, water, diet, radiation, and exposure to infection—and it subscribes to the overarching assumption that every trait of every organism is the product of some set of interactions between genes and the environment.
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The debate over the relative contributions of genetics and environment—"nature versus nurture"—remains unresolved in many fields of study, from education to animal behavior to human disease. Historically, scientists assumed opposing viewpoints, choosing to favor either nature or nurture, rather then exploring the ways in which both play critical and complementary roles.…
The English anthropologist Francis Galton (1822–1911), a cousin of Charles Darwin, conducted some of the first reported twin studies. Advancing his cousin's theories of evolution, he performed twin studies in 1876 to investigate the extent to which the similarity of twins changes over the course of development. He is considered the originator of the field of medical genetics because …
The role of genetics in determining a person's intelligence is a controversial subject. Few would deny that genes play some role, but many are uncomfortable with the idea that genes determine intelligence. For if intelligence is a genetic trait the implication is that some people are born to be smart, others are not, and education and upbringing cannot change it. The results of scores of st…
Although other species communicate with one another, speech is unique to humans, prompting scientists to question whether the ability to speak is determined genetically. In 1871 Darwin suggested that speech might be inherited when he observed that "man has an instinctive tendency to speak, as we see in the babble of our young children while no child has an instinctive tendency to bake, brew…
The question of interest is no longer whether human social behavior is genetically determined; it is to what extent. —Edward O. Wilson, 1978 Heredity is what sets the parents of a teenager wondering about each other. —Laurence J. Peter Studies of families and twins strongly suggest genetic influences on the development and expression of specific behaviors, but there is no conclusive …
In many instances it is difficult to understand how genes manage to assert themselves over the myriad of complications imposed by the environment. The Environmental Genome Project (EGP) was launched by the National Institute of Environmental Health Sciences (NIEHS, which is one of the twenty-seven institutes and centers of the NIH) in 1998. The EGP aims to improve understanding of human genetic su…
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