It's good to see how many GCers are on the same page about this!
I went to a private school. We had basic sex ed in eighth grade and a semester-long Health class, which included all kinds of sexual topics, in tenth grade. Both were required, but since it was a private school, you could say that parents all consented to it. One new girl's mother did raise a stink because she didn't want her daughter to learn about oral sex.
I'm willing to bet she learned about it one way or the other.
The swimming pool analogy is a good one. Another good one is the Ferrari analogy: If you have a racy new Ferrari the kids aren't allowed to drive, telling your kids not to drive it is a good idea. Removing the seat belts and air bags from the car is a bad, bad idea.
Ivy