system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do many cultures see/teach sexuality as being immoral?

I've seen some people answer this question by saying "because of religion," but that doesn't answer the question, because religion is a human construct, so why would religion teach sexuality as immoral in the first place?
gpt
Keep in mind most modern religions were founded thousands of years ago. During this time sex and other related acts were very unsafe. You could easily contract a venereal disease or get your (or your partner) pregnant. Some forms of venereal disease, were pretty much a death sentence, and women quite frequently died in the process of child birth. By having an authority figure (religion in this case) tell people to restrict these acts or anything similar, they were keeping their followers alive.