achievement discrepancies

In one, 30% come from broken homes and in the other 60%. I know I should not be that surprised because I suppose their families should matter that much, but I am. I would guess they would be just as surprised. She was told she was depressed due to the split but she could not feel it. It probably affects her and others in ways they do not even understand. If that hurts I wonder what damage the rest of life can do. What might be going on with the others?