That's how it is in my family. My sister and I take after my dad. We are not large, but not thin, wheras my younger brother and younger sister are both have a smaller structure to there body. That is how ot was for Olga, Tanya, and Alexei. I think Anastasia and Maria's bones were differently, as in their shoulders and hips went out farther. Even if they dieted and excercised, they would never look like their siblings. (This is my oppinion)