Genes versus Hormones in Homosexuality

It is clear, however, that the cause of homosexuality lies in some unusual balance of hormonal influence in the womb but not later on, a fact that further supports the idea that the mentality of sexual preference is affected by prenatal sex hormones. This is not incompatible with the growing evidence that homosexuality is genetically determined. The "gay gene" that I will discuss in the ext chapter is widely expected to turn out to be a series of genes that affect the sensitivity of certain tissues to testosterone. It is both nature and nurture.

It is no different from genes for height. Fed on identical diets, two genetically different men will not grow to the same height. Fed on different diets, two identical twins will grow to different heights. Nature is the length of the rectangle, nurture the width. There can be no rectangle without both. The genes for height are really only genes for responding to diet by growing.

Matt Ridley, The Red Queen: Sex and the Evolution of Human Nature (2003-05-01)

• embryonic development
• evolution
• homosexuality