information:filtering
Evolutionary perspectives

Since homosexuality tends to lower reproductive success, and since there is considerable evidence that human sexual orientation is genetically influenced, it is unclear how it is maintained in the population at a relatively high frequency. There are many possible explanations, such as genes predisposing to homosexuality also conferring advantage in heterosexuals, a kin selection effect, social prestige, and more. A 2009 study also suggested a significant increase in fecundity in the females related to homosexual people from the maternal line (but not in those related from the paternal one).