《颜氏家训·后娶篇》
异姓之子受宠则父母遭怨恨，后母虐待前妻之子则兄弟成仇敌，家庭里发生这类事情，都是家里的祸患。
异姓宠则父母被怨，继亲虐则兄弟为仇，家有此者，皆门户之祸也。
If children of different surnames are favored, parents will be resentful. If a stepmother abuses the children of her ex-wife, then the brothers will become enemies. If such things happen in the family, they are all disasters in the family.