Are there gay genes? Sociobiology and homosexuality

This paper considers recent hypotheses prepared by sociobiologists purportedly giving Darwinian evolutionary explanations of human homosexuality. Four models are considered: balanced superior heterozygote fitness, kin selection, parental manipulation, and homosexuality as a maladaptive side effect of intensive natural selection for superior male heterosexual behavior. The evidence for the models is reviewed, and their philosophical adequacy is considered in some depth. It is argued that although the models pass obvious methodological hurdles and meet other criteria, as yet, the evidence for their applicability is indecisive.