they tried the doll/car meme on monkeys, and overall the males preferred the cars and the females the dolls...
also some stuff about chimps: http://news.nationalgeographic.com/news/...evolution/
obviously we are born without exact knowledge but not without genetic predispositions, and a child has many years of developing before we are going to see the full effects of their genetics. A child not having a beard does not mean he will never have one; he still has the genetics for it even if you see zero traces of it for years. I also saw a study where they figured out that rats could "remember" smells across generations; basically the offspring of rats exposed to a certain smell reacted to it differently than other rats. in this sense a certain kind of "knowledge" could be genetic. I guess this is where standard kind of heterosexuality could come from, at least partly.
for other human sexualities I think there is a convergence of genetics and cultural factors, possibly triggering each other. This is just an idea though.
I noticed connections between homsexuality and pedophilia, cause a lot of gays apparently got raped as kids which turned them gay. This was just from a bunch of interviews I saw in a vid though, idk how true it is. it may be that this is a fixation with certain physical things, which could be heavily imprinted on someone very young. If this is true then I would guess that this kind of experience could also affect people differently; it could be triggering certain genetics with some, but not others, and have different, varying results. I think some of us have probably heard of all the pedophiles and homosexuals in Hollywood. I haven't watched this vid but it seems related: https://www.youtube.com/watch?v=g0V_j8G3cNQ
It's a really interesting topic to me, because I do feel that the tumblr/SJW sexualities are a bit of a mess and probably not adhering to reality anymore, yet my own sexuality would fit right in with the least sensible tumblr memes, and there's really nothing in my past that explains it aside from things that could have happened when I was little which I would have forgot (trauma?).