From Canada, there is this study:
It's a question which has troubled science since Darwin: if homosexuality is, at least in part, inherited, how are those genes being passed down to new generations?
Canadian researchers say they have found the first evidence to back up the theory that gay men have the evolutionary advantage of being "super uncles", a way of enhancing the survival prospects of close relatives and — indirectly, at least — making it more likely their genes are passed on.
Paul Vasey, associate professor in the University of Lethbridge's department of psychology, said his research found evidence that gay men may be more willing to support their nieces and nephews financially and emotionally.
The idea is that homosexuals are helping their close relatives reproduce more successfully and at a higher rate by being helpful: babysitting more, tutoring their nieces and nephews in art and music, and helping out financially with things like medical care and education.
The question of whether homosexuality clashes with evolution has puzzled scientists for decades. The trait appears to be inheritable — but because homosexual men are much less likely to produce offspring than heterosexual men, researchers have struggled to explain why the genes for the trait weren't extinguished long ago.
"Maybe it's in this way that they're indirectly passing on at least some of the genes that they're sharing with their kin," he said.
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