If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
Notes for future OT posters:
1. Please add the 'open_thread' tag.
2. Check if there is an active Open Thread before posting a new one. (Immediately before; refresh the list-of-threads page before posting.)
3. Open Threads should be posted in Discussion, and not Main.
4. Open Threads should start on Monday, and end on Sunday.
As I understand it, humans are on the spectrum between have maximum number of offspring with low parental investment and have a smaller number with high parental investment. There are indicators (size difference between sexes, size of testes, probably more) which puts us about a third of the way towards the high investment end. So, there's infidelity and monogamy and parents putting a lot into their kids and parents abandoning their kids.
Humans are also strongly influenced by culture, so you also get customss like giving some of your children to a religion which requires celibacy, or putting your daughters at risk of dowry murder.
Biology is complicated. Applying simple principles like males having a higher risk of not having descendants won't get you very far.
I'm reminded of the idea that anti-oxidants are good for you. It just didn't have enough detail (which anti-oxidants? how much? how can you tell whether you're making things better).
Or cultural variation is mostly determined by genetic variation. It's hard to empirically distinguish the two.