Sex plays noticeable role in humans culture and interactions. I remember, that I was very confused, when I've started to learn classic literature in middle school, just because I didn't understand the role of sex in life of people. There was a great gap between my child books, which didn't contain any info about sexual relationships between adults, and these classic novels, where the significant part of conflict is based on sexual relationships sometimes!
Of course, they didn't contain sex scenes, but they were partially based on implications of sexual relationships. There was no chance to understand the basis of the plot and conflict without understanding sex. First and second kinds of books were like from different worlds... and there was NO smooth transition between them.
For example, I didn't understand, why in these novels the wife is upset, when her husband cheat on her. And sometimes in such a degree that it leads to tragedy! NOBODY explained me, that in monogamic couples sex plays a role of something, which makes people in couple feel unique and especially close for each other. And that's why if the husband cheat on wife, she feels betrayed.
Of course, I just couldn't understand how can sex make people close and unique to each other, since I was told that sex is like a going to the toilet! So I couldn't understand any conflicts, based on cheating, either! But when I've asked about it, everyone looked at me, like I'm stupid and it should be understandable by everyone by default. Or said that I should grow up, to understand. So I felt strongly inadequate.
I'm still angry about this situation. First people told me inadequate things, and then the same people pretend that I am inadequate! ¯_(ツ)_/¯ It was really humiliating and absurd.