Homosexuality is either genetically or environmentally determined. Environmental influences are either intrauterine or postnatal. Behold the universe of possibilities!
Sexual orientation probably results from the interaction of environment and genetic predisposition, but science, so far, explains only a little. Voluntarily choosing homosexuality cannot be discounted, although the more deeply embedded in genetics or early experience homosexuality is, the less voluntary it is likely to be.
A related characteristic, sex, is equally mysterious. The sex ratio at birth, for example, sometimes changes in response to environmental conditions. Severe drought results in Australian aborigines who still live in their traditional surroundings having more girls than boys. Similarly, according to Ralph Catalano of the University of California, Berkeley, the dissolution of the communist grip on East Germany (and the ensuing severe economic dislocation in 1991) was followed by births of more girls than boys. These findings make it appear that male embryos are more vulnerable to a harsh intrauterine environment. If adversity differentially impedes male development, might it account for some tendency toward male homosexuality?
Very harsh postnatal conditions may also select for homosexuality. If, for example, rearing children is fraught with great...