I mistyped. > A gay person would have to result in their siblings having 2x as many children Should have been: > A gay person would have to result in their s

I mistyped. > A gay person would have to result in their siblings having 2x as many children Should have been: > A gay person would have to result in their siblings having 2x as many additional children Here's the math: An individual's children have 50% of their genes. Their nieces and nephews share 25% of their genes. Therefore, if the hypothesis is that homosexuality evolved to promote the production of nieces and nephews at the expense of producing direct offspring, this adaptation would need to result in at least two nieces/nephews for each offspring that the homosexual individual would have produced directly. So, if we assume a stable population where each couple produces 2 offspring, a gay person would be giving up producing 2 of their own children. In order for this strategy to break even, it would have to result in their siblings producing 4 offspring, in addition to the offspring that they would have had anyway. Possible, but not likely. On top of the math just being heavily stacked against this being an explanation, there are other reasons why it is unlikely: 1. If this were a successful strategy, you would expect to see a much higher prevalence of gay people than we currently do (<5% of the population). 2. There are already adults who take on this hypothetical role of assistant to the breeders: grandmothers. And they avoid the fertility tradeoff because they are evolved to stop being fertile at a certain point in their lives.