I think it's without question some of the Eastern European gymnasts of old were on something that kept them from growing and developing. As far as the Americans, I think they merely starve themselves. If you have minimal body fat, your body doesn't produce as much estrogen. Witness the fact that anorexics don't get their periods. Once female gymnasts start eating normally and have normal body fat, they get their periods and grow boobs. Aly is still a svelte young woman, but compared to her Olympic body she has blossomed considerably. I think Shawn was fairly round in terms of hips and boobs even when she was competing in gymnastics. Her development seems less extreme.