Some line comes to mind about a "herd of independent thinkers". ;-)
We should have a set of booklets: "Oh, I see you're having 11th Grade Crisis Type 2! Here's your booklet!"
Iirc, all this girl's questions are answered in Did Adam and Eve Have Belly Buttons?
However, the deeper problem for many adolescents is that they simply don't wish to accept that something they want to do is a sin. Time knocks that out of many, but not all.