A similar point to the swearing and censorship thread, why is sex such a controversial subject for youth in the first place? One of the very reasons for it being an area of interest for youngsters is the fact that it's forbidden to them.
Teenage pregnancy has only become an area of concern in recent decades. No wonder, really, when you consider the media is incredibly sexual, people are conditioned to be interested in sex, and then there's an outcry when there's a "problem" with underage sex. To be honest, it wouldn't surprise me if there's an ulterior motive amongst those in power when you look at the whole picture; teenage pregnancy is a hot topic of discussion everywhere, in the news, television, in politics. Things like this don't just happen for no reason, but I digress.
The current way in which society treats sex is incredibly contradictory. Society throws sex around everywhere to the point where it is unavoidable, the majority of children will learn about sex at a very young age; and then most of the time they are immediately taught that it's something that is dirty, forbidden, and is to be avoided, which only raises interest in it. We can either go back to our traditional ways and keep sex entirely private in every way possible; or, a more reasonable solution, forget about teaching abstinence, secrecy, and maintaining the "innocence" of children, and amend the age of consent laws whilst focusing entirely on safe sex practices. If there's no risk of pregnancy or STDs, then is there really anything wrong with having sex at all?