Sex education is not taught in elementary school, which is a good thing since you really should know your multiplication table before you know how to multiply.

But that does not mean kids don’t think about it at all. By the time they’re 8 or so, they realize babies are not the product of overactive parental imaginations that create children springing from cabbage patches or delivered by storks. Because by 8, they notice there are certain fat women who are not fat, but having a baby. That blows the “Well, babies just are” theory of procreation all to hell.

(Though it never ceases to amaze me how kids, when told “A baby comes from a mommy’s tummy,” are satisfied with that. Because my first reaction was, and still is, “How the hell does it get out of there? Where’s the escape hatch, because ain’t no way a kid is sliding out of there without some serious arguments from mom.”)

Bryson’s theory of where babies come from has advanced lately. About a year ago, he knew it happened when a boy and a girl pushed their privates together. If this were technically true, every woman who’s ever ridden the Tokyo subway would be pregnant. “I don’t know, doctor, when I boarded everything was fine, by the Ginsu District I was suffering from morning sickness.”)

Bryson and I were watching TV the other night (who needs the sex talk when you can just watch The Simpsons, right?) when, as Homer was filling Bart in, my own son turned to me and said, “I know how they do it.”

“Do what? Animate this show? Come up with all the funny voices? Get away with the talking about sex during family hour? Wait, scratch that last one.”

“You know. How a boy and girl have a baby? I’m not sure how I know, but I know. Maybe mommy told me. Or you.”

Or, more likely, one of his 9-year-old friends. I would have liked to have been the one to fill him in on the whole sex thing, but I would have waited for a more comfortable age. Like when he was old enough to drive. Himself to the retirement home.

But when he’s 9? If I were to fill him in, the conversation would be a confusing mix of “his thing” and “her deal.” Bryson would understand it about as much as he does the need for triple-digit addition (“Isn’t that what cash registers are for?”).

So I was more than happy to hear him out.

“OK, so what happens between a man and a woman?”

Now I would have said to that, “That explains why you’re single.” But Bryson, ever innocent and understanding, said, “OK, it starts with boy who, well, I don’t want to say it, but –“

He places both hands over his groin and continues without pausing.”

“-he puts his MMM-mmm into a girl’s, something, and you get babies. Now I don’t want to talk about it anymore.”

Bryson is assuming, of course, that the girl wants anything to do with the boy’s MMM-mmm, because maybe the guy’s a real MMM-mmm-head.

But that’s a topic for another conversation.