As far as animal sex was a subject we saw occasionally cows having sex on the meadows and in the countryside everybody knew about that, but I had not connected the cow behaviour to human behaviour by then. But it was like a flashlight when a documentary about dolphins showed underwater footage of the mating and actual intercourse in great detail. It was a bit embarrassing because the similarity between the sex organs of dolphins and humans is quite simple to see. But that was after I had lost my believe that babies are created by kissing. lol.