I didn't even bother reading that other thread.
When I was 13 I wished I was not a virgin....Hell...I still wish I was not a virgin.
Anyway.......When I was 13, I was in the 8th grade. There's a reason that they taught sex-ed and we knew about condoms back then.
Your kids will be sexually active at that age. Get over it and learn how to be a good parent.