Why, you ask?
Partly because many of my books are centered around gay teen characters, but a lot of the time, it's because sometimes, my characters have sex.
People are weird about sex. They're even weirder about teens having sex. ESPECIALLY in fiction.
Why is this? Because they remember what it was like to be a teenager? Because they don't?Because they want their own kids to wait until an appropriate time? Because their own morals say it's wrong?
My take on it is this: with many of our teenagers entering high school with no knowledge of safe sex practices, where do they get their information? TV, Movies, and Books. Being a teenager is awful sometimes: you're loaded up with hormones, you're trying to figure out who you are and what you want out of your life and a lot of the time, you're really confused about all the feelings that are going on in your body and mind. Being assured that sexual feelings are normal can really help emotionally. Surrounding sex with a stigmata will only make teens want to do it more--and they might not be prepared to deal with the consequences.
A parent has every right to limit what their teens read or watch, of course. But from my experience, any book that I was told I couldn't read, I would take the first chance I got and locked myself in the bathroom to read it.
Teenagers have sex. Sometimes they do it safely, sometimes they don't. Educating them a little more about their bodies and feelings--in fiction or non-fiction would be a great boon to them.
Plus, who doesn't love some torrid (but tasteful) romance?