Personally I believe that parents and the school should work together in this one. Parents would tend to feel awkward talking about these kind of things to their children that's why the school would be there. Still there are things the student want to ask but can't really ask the school for some reason, that's where parents come in. Other than that, parents are the ones who really should teach the morality on why there is sex ed, that having a family is something serious. The school can't really teach the child certain things a parent could.
I've mentioned on my previous posts that i'm for sex ed because its much more safer. Its also more assuring. In a conservative country like the Philippines, having sex outside marriage is always kept secret but not inexistent. Teaching sex ed would not only help people here realize these kind of things but be also aware of the consequences of these "taboo" in society.