1515) Boiled down to its core, everything criminologists have learned about crime in recent research is that most adolescents who become delinquents, and the overwhelming majority of adults who commit violent crimes, started very young. They were the impulsive, aggressive, irritable children who would not obey their parents, bullied their neighbors and acted out when they got to school. Because they are accustomed to getting their way by physical force, they see no reason to change. They actually like the way they act, and this makes it increasingly difficult to reverse their anti-social proclivities. After age eleven or twelve, their cases seem intractable [...] Modern research suggests that there are positive alternative treatments. Many factors go into producing personality: temperament, the genetic component you are born with; the neighborhood in which you grow up; and perhaps most important, the style of your parents.

Fox Butterfield
All God's Children (1995)
quoted in a review by Robert Stone,
"The Sins of the Fathers" in
New York Review of Books (11/2/1995)

1516) [T]he psychic and physical characteristics of human beings, and the differences between individuals, are the consequence of an interaction between the genes that are present in the fertilized egg and the sequence of environmental circumstances that the developing organism experiences during its life cycle. With a few exceptions [...] human characteristics are all subject to this interaction of forces. There are, morever, random events in cell growth and differentiation that are neither genetic nor environmental in the usual sense, and which play an extremely important part in development, especially in behavioral traits.

An important consequence of the unique interaction between internal and external forces [...] is that knowledge of genetic differences contain no information at all about whether a characteristic can be changed by environmental and social arrangements. The most elementary error about genetics and development is to suppose that "genetic" is the opposite of "changeable" and that an answer to the question "how much can a trait be changed by social, historical and individual circumstances" is given by an answer to the question "how important are genes."

[...] Genetics is the study of similarity between relatives, and the problem of human genetics is that, in a species with a family and social structure and a taboo against manipulating individual life histories experimentally, there is a confounding between the similarity of relatives that arises from biological causes and the similarity that arise from social causes.

To say that genetic differences are relevant to hetero- and homosexuality is not, however, to say that there are "genes for homosexuality" or even that there is a "genetic tendency to homosexuality." This critical point can be illustrated by an example I owe to the philosopher of science, Elliott Sober. If we look at the chromosomes of people who knit and those who do not, we will find that with few exceptions, knitters have two X chromosomes [women], while people with one X and one Y chromosome [men] almost never knit. Yet it would be absurd to say that we had discovered genes for knitting. [...] [I]n our culture, women are taught to knit and men are not. The beauty of this example is its historical (and geographical) contingency. Had we made our observations before the end of the eighteenth century (or even now in a few Irish, Scottish and Newfoundland communities), the results would have been reversed. Hand knitting was men's works before the introduction of knitting machines around 1790, and was turned into a female domestic occupation only when mechanization made it economically marginal.

R[ichard] C. Lewontin
letter to the editor
New York Review of Books (11/2/1995)