Since ever. (and since the invention of alcohol)
I was born in the 1960s. You got one talk, if that, and rarely did the issue arise again unless you were (1) caught in the act or (2) becoming a parent.
My mother was (originally) a Roman Catholic. She gave me the talk and mostly informed me about how the female reproductive system works. (It's obviously more complex.) She was uncomfortable doing it. I had a better understanding of how female periods and/or conception works than most of the girls in my class.
I was not uncomfortable talking to my daughter about sex, but I did get annoyed and thrown off kilter when I found her alone in her room with her boyfriend and/or girlfriend and/or the day she thought she was pregnant. (These situations did not all occur at the same time, by the way, and the events in the bedroom where not the ones leading to a pregnancy scare.)
But to stay on topic, I am confident that so far she has not taken it up the butt.