If homosexuality is not entirely genetic in origin, where does it come from? In exploring claims that homosexuality is genetic, the Columbia University researchers — Byne and Parsons — emphasize an extremely important point. In their own model, which they describe as “a complex mosaic of biologic, psychological and social/cultural factors,”
… genetic factors can be conceptualized as indirectly influencing the development of sexual orientation without supposing that they either directly influence or determine sexual orientation per se. Similarly, one could imagine that prenatal hormones influence particular personality dimensions or temperamental traits, which in turn influence the emergence of sexual orientation. [1]
This last point concerning personality dimensions and traits is not an obvious one. The popular accounts of the biology of homosexuality uniformly avoid it. It is much easier to ask the meaningless, but subtly bias-inducing, sound bite question, “Isn’t homosexuality genetic?” than to ask the much more realistic — but frustratingly complex — question, “To what degree is homosexuality (or any other behavioral trait) genetic and nongenetic, innate and acquired, familial and nonfamilial, intrauterine-influenced and extrauterine-influenced, affected by the environment and independent of the environment, responsive to social cues and unresponsive to these cues, and when and in what sequence do these various influences emerge to generate their effects and how do they interact with one another; and after we have put these all together, how much is left over to attribute to choice, repetition, and habit?”
One way to simplify and begin to approach at least part of this very complex question is to note that the genetic contribution to a given trait, behavioral or otherwise, need not be direct; actually, when the trait is behavioral, the genetic contribution is usually not direct. In other words genes often contribute to some other phenomenon that in turn predisposes an individual to a given behavioral response.
An obvious example of this principle is basketball. No genes exist that code for becoming a basketball player. But some genes code for height and the elements of athleticism, such as quick reflexes, favorable bone structure, height-to-weight ratio, muscle strength and refresh rate, metabolism and energy efficiency, and so on. Many such traits have racial distributions (which makes the genetic connection evident), resulting in more men of Bantu or Nordic stock (being taller) playing on professional basketball teams than men of Pygmy or Appenzeller Swiss stock (being shorter).
Someone born with a favorable (for basketball) combination of height and athleticism is in no way genetically programmed or forced to become a basketball player. These qualities, however, certainly facilitate that choice. As a consequence the choice to play basketball has a clear genetic component, most evident in the high heritability of height. Were scientists to undertake a study of basketball-playing comparable to the studies that have been done to date on the genetics of homosexuality, they would find a much higher degree of apparent genetic influence. In summary, the strong genetic correlation does not mean that people are forced to play basketball.
In an effort to counter much of the nonsense being promoted nowadays in the press, the editors of Science, one of the premier scientific research journals in the world, devoted a recent issue almost exclusively to “Genetics and Behavior.” In the opening editorial, Torsten Wiesel, president of Rockefeller University, one of the leading international centers for genetics research, comments:
The operations of the brain result from a balance between inputs from heredity and environment — nature and nurture — and this balance should also be reflected in research into the biological basis of behavior. [2]
[1] Byne and Parsons, “Human Sexual Orientation.”
[2] Wiesel, “Genetics and Behavior,” Science, p. 1647.
Satinover, J. (2004). Homosexuality and the Politics of Truth. Grand Rapids, Michigan: Baker Books.
