Saturday, February 2, 2013
While female sexuality appears to be more fluid, research suggests that male gayness is an inborn, unalterable, strongly genetically influenced trait. But considering that the trait discourages the type of sex that leads to procreation — that is, sex with women — and would therefore seem to thwart its own chances of being genetically passed on to the next generation, why are there gay men at all? Put differently, why haven't gay man genes driven themselves extinct? This longstanding question is finally being answered by new and ongoing research. For several years, studies led by Andrea Camperio Ciani at the University of Padova in Italy and others have found that mothers and maternal aunts of gay men tend to have significantly more offspring than the maternal relatives of straight men. The results show strong support for the "balancing selection hypothesis," which is fast becoming the accepted theory of the genetic basis of male homosexuality. The theory holds that the same genetic factors that induce gayness in males also promote fecundity (high reproductive success) in those males' female maternal relatives. Through this trade-off, the maternal relatives' "gay man genes," though they aren't expressed as such, tend to get passed to future generations in spite of their tendency to make their male inheritors gay.