I think we've always been obsessed. Back in the day people were obsessed with whether you've had sex or not, a woman's virginity (What? Pregnant out of wedlock? You whore, scum of the earth!" How you have sex, and whether a penis is meant to go up the ******* or not. Human morality was pretty much graded on a scale of "Missionary position in marriage only" to "I'm Homosexual"
And now we have cultures where the opposite genders don't interact with each other at all outside of the family, just in case they end up having sex.
Not sure which one I prefer tbh!