A friend of mine has a pubescent son who is showing signs of interest in sex and the pleasures of his own body.
I think many kids are embarrassed by having the world of sex and the world of their parents mix, or even touch. So instead of "an earnest talk", I suggested getting the kid a couple of books, and not even handing them to him, but placing them on his shelf for himself to find.
I know I would have preferred that when I was young (And it was pretty much what happened). Don't you think many kids are like that too?
Or maybe another way is to have a friend of the family do The Talk. But personally I think it's too big a subject to be covered in a talk, I think some study is the ticket. Of course I was very much a Reader from an early age. What do you think?