Incest varies greatly by culture. For instance, you gave ancient Egypt, Greece, and royalty in the Middle Ages as examples of historical incest being common, that for "99.9% of Human History" it was so. But I can name an equal number of historical examples where it was, in fact,
not OK. The Romans generally despised incest, which is why Caligula's enemies used accusations of it to slander him. The Israelites / Jews prohibited incest (though I
think they only considered it so if it was parent-child or sibling-sibling; I could be wrong). Around 1700 BC the Babylonian Hammurabi Code prohibited incest as well. So, I think your blanket argument that it was almost always OK through history until roughly the last century is inaccurate. It depends on the culture and time in history.
I meant nowadays. When I talked about it being "normal" in terms of typical human behavior, I was specifically referring to today, not to the past. (I thought my mention of today's population would've made that clear, but apparently not.) Citing historical examples doesn't tell us anything about how common it is right now, which was the focus of my post.
Laws don't mean much. Your mention that a lack of laws against incest tells you it's common and acceptable is a reach. There aren't laws prohibiting calling someone "wall stucco", but I doubt very many people actually call anyone that. There is also a ridiculous law against carrying an ice cream cone in your back pocket. I doubt anyone in that state thought doing so was immoral, though. An absence of law simply means the lawmakers in a nation don't feel the need for a law, which could be for various reasons; it doesn't tell us anything beyond that.
It's probably only immediate family to me. TBH, beyond immediate family relations, I don't know that I would consider it incest (though I think most if not all U.S. states prohibit first cousins as well). I did mention my own cousins, but I had been thinking more in terms of the genetic lack of attraction among family members, not about what does or does not qualify as incest. So I'm not sure I would agree that extended family qualifies. I'm not saying it doesn't; I'm saying I haven't really thought that deeply about it.
It's possible, but not by default true that smaller communities automatically mean incest is more common. It depends on how small the communities are. If they are extremely small (say, a hundred people or fewer), incest is much more likely, but if you have a community of a thousand or more, I would guess it's not very common even then. I would again mention that I was referring to incest today, in 2019, not historically, even in 1819 or 1919. That said, even back then, I'm not sure I would really consider first cousins marrying as incest. As you mentioned, times change, and I think what qualifies as incest also changes over time and culture.
Agree to disagree. Whether you accept my points from either the last post or this one, I was merely expressing an opinion and using things like population statistics to show where I got my thinking. As an opinion, you don't have to be on board with what I say. I don't find this topic important enough to do a lot of back and forth, although I don't mind talking a bit like we've done.
Anyway, cheers for the discussion.