Yes. During times of famine, it was found that the more attractive siblings had better survival rates because the parents were allocating more resources (food) to the most attractive ones. Mothers are also more likely to buckle in visually attractive children into grocery carts and keep them wandering from sight. Attractive siblings also tend to have higher expectations from their parents too. Fat is just not attractive. It's just the way the world works. These are processes built in biologically through evolution that fat tumblerinas will never change. :)