What are they feeding these girls?

Spent the day at the pool with the kids and what a eye opener it was. As I said before I have a 13 year old boy and his eyes were popping out of his head. What's with these young girls today? I mean 13 yr olds with bodies that are shocking, and many of them know it too! I'm pretty sure that back in my youth I looked good, but not that good! At 13 we DID NOT have boobs like that! It's scary to the mom of a boy. I want to sheild hom from seeing these girls, even though I know it's not realistic. He's growing up too fast. Can't I just lock him in the closet and pick out his wife for him?