What's some sex ed info you didn't know until embarrasingly late?

I meannnnnn I'm pretty sure my mom still thinks this. When I was a late teen / young adult, we watched the movie "Quest for fire" together.

When one of the protagonists starts having sex with one of the women, doggy style, my mom said "Well they won't get very strong children doing it this way". An idiom in French Canada to say conception won't happen.