I'll have to do some digging to find the studies when I'm not at work. But research in rats, bonobos, and other mammals have shown gay population increase as overpopulation increases. And then surprisingly the gay rats or bonobos will then care for the children when childcare becomes inadequate. Like gay male rats keeping the babies warm, etc.

It's still just a theory and there isn't entirely enough evidence to support it as cold hard scientific truth, but it's something to think about when people say that it's detrimental to society or the population as a whole, and anthropologically speaking it makes sense, no?

However, my outrage here isn't because I am adamantly opposed to incest. Honestly, I'm really far less interested in what they do behind closed doors if it's not abusive and it's consenting between adults. BUT my outrage here is the conflating between gay sex and incest. This is that whole "gross" factor creeping out again. "We think homosexuality is gross, but we let them do it! so incest should be ok too, right?!"

Why not just make the argument of "These are consenting adults spending time in their bedroom as they please. The 4th amendment and the right to privacy protect that.(this was in the UK tho...so whatever the equiv is)" Why? Because of the inappropriate connection between the 'gross' acts of homosexuality and incest.

It's offensive, it's subtly hateful, and it's part of the language of destruction that leads to youth in our community to feeling so hopeless and wrong that they commit suicide.

edit: Here's a small article discussing homosexuality in evolutionary context