Sex and philosophy

The other day I read a tweet by a woman, sarcastically and rhetorically wondering aloud how the (then) “most recent mass shooting was going to be blamed on pussy.” She used a term I had never heard before: ”incel“. I looked it up and went down the rabbit hole, learning a lot. It stands for “involuntarily celibate.” You can look up how it all started if you care. But for my discussion here, I’m interested if philosophy has any insight into sex, or is sex just deemed another bodily function, an instinct, that is beneath or beyond the realm of philosophical inquiry?

I’m working on some ideas but I’m not so sure they are not really just sociology, biology, psychology, etc. I don’t want to wax on if this is not the proper forum. But I would like to have an answer to the question just asked, above. If philosophy does address sex, how is the line drawn between that which is philosophical and that which is another discipline? My inclination is that everything is an open target. Regardless, what does philosophy have to say about sex, if anything?