This is one of those subjects which tends to inspire a bit of "you're not a parent so you don't understand." Which I sympathize with, some, but not when it comes attached to some barely disguised version of "Daddy can't handle the thought of his darling daughter having sex."
Teens are going to have sex. Many of them are having sex a much younger age than people like to imagine. I'm not sure why. People started having sex pretty early when I was a teen, and they probably did when you were teens too. Lots of 9th and 10th graders have sex. So, uh, deal with it.
