> If it was 20%, it means that person from every family (wrt. parent's incomes) has equal chance to end up rich or poor, meaning that there is nothing that pare

> If it was 20%, it means that person from every family (wrt. parent's incomes) has equal chance to end up rich or poor, meaning that there is nothing that parents could do to help their child. That's not true. It would just mean that the parents' financial circumstances have no bearing on their ability to help their children.