BACK in 1993, when Dean Hamer discovered what appeared to be a gene that predisposed men to homosexuality, he created a paradox. According to Darwinian thinking, if homosexual men have fewer children than straight men the “gay gene” should quickly disappear from the population. Yet we know that homosexuality persists.
So what is the mechanism that keeps the gene in circulation? Perhaps gay men are good at looking after their straight brothers, who share a proportion of their genes. That way, the gay gene may be passed on by the brothers of gay men, even if they themselves have no…
