There are books which contain explicit depictions of sex between teenagers. Why do you want teenagers thinking that having sex before you are 18 is normal? Kids shouldn't be reading stuff about sex (gay, straight, or otherwise) before they are adults. The only people who would be opposed to that sort of thing are groomers.
A lot of people replying to this skipped over part of this comment.
I DO NOT AGREE WITH THIS ARGUMENT. I AM JUST PUTTING IT HERE TO ANSWER THE QUESTION!!!!