I found out about sex when I was two. Being of an enquiring mind at that age, as I always have been, I asked my mother where babies came from, and she told me... well, not everything. Kind of the basics. I knew there was a "baby hole", as she put it. But she gave me a very watered-down version of what happened. As you probably would if you were trying to explain sex to a two-year-old. It involved switches.
I, of course, didn't know what to make of it, so I went back to thinking about dinosaurs. By that point, I could spell "hypsilophodon", so evidently that was the right field of study for me at the time. I never forgot the conversation, though.
I didn't actually know about the mechanics or anything until about ten or eleven, but a couple of years earlier, a lot of other people in my primary class got to know about it from the sex education video they showed in year 5. I was unwell that day, but I kind of knew everything anyway. (Or most things. I still don't know everything - who does?) It was evident the day afterwards who hadn't been told at any point beforehand, as they clearly thought it was totally disgusting - as, at that age, did I, although I'd already known about it so I was prepared; by the age of twelve, though, I was pretty interested in it, as you'd expect. As far as I'm aware, the WORST THING EVER IN THE WORLD scale goes like this:
Nursery school: someone's got your sweeties
Infant school: being in love
Junior school: having sex
Secondary school: not having sex
University: having never had sex
Adulthood: someone's got your sweeties
This strange middle-ground of "you've had sex!" being used as an insult lasted until year 7, when the few people who didn't know - those whose parents signed the form and sent it in, necessitating their children to leave the classroom and pray for our souls - finally found out. Which, of course, had me wondering what they had been told all these years. Does anyone actually tell the stork story any more? Don't they know he was captured in Yoshi's Island?
And, finally, today I got to wondering further. When did you find out about sex? How? What did you think at first? I'd love to know.