There's a traditional view of sexuality that men are only sexually attracted to women, and vice versa, and that's normal and everything else is not normal (kinky). The more we learn about sex (and gender) the more we learn that there are very few completely "normal" people out there, and a lot of people who are a bit kinky in one respect or another. I think it's now accepted that the hetero-homo thing is a spectrum rather than a binary state, and the primary reason people of the same sex don't have sex with each other is societal pressure rather than biological attraction. e.g. women tend to experiment more with this because society has a more lenient view of "girl-on-girl" than male homosexual sex.
My personal opinion is that evolution "wants" everything to fuck everything as much as possible, just to see what happens. The best reproducers are the ones who did the most fucking, after all. But we're getting into Oglaf territory here.
It's a term rooted in the conditions that make sex a reproductive act and not just something that feels good
Why are you projecting your own biases into my statement? Call a spade a spade. What you take away beyond that is on you.
You grouped all sexual activity into two groups: "normal" and "not normal". I think if anyone is projecting bias, it's that.
Personally I suspect the issue here is that incest is the only form of sexual activity that we have a natural proclivity against, probably because of evolutionary pressure (as in, hard-wired into our DNA) against fucking blood relatives. Because a consistently-inbred population will breed itself into oblivion. People who fuck kids can still successfully reproduce and society trundles on.