Ren

"I probably wouldn't have been so
easily influenced by my friends either. I can easily see how in a true
unschooling home where all are given respect and personal freedom, a
young teen would feel comfortable enough to *not* engage in sex
physically."

A factor I haven't seen discussed is the whole peer pressure issue. Kids that attend school all their lives are hugely affected by what their friends think (most of them anyway). I remember doing things just because my friends had tried it or because they pushed me to do something before I was ready.
I'm fairly sure I wouldn't have tried pot or cloves if it hadn't been for the fact that I wanted to look "cool". I found myself in some very unsafe situations due to peer pressure.

Ren

"I never teach my pupils; I only attempt to provide the conditions in which they can learn."
Albert Einstein