If family members are taking advantage of your weaknesses, then they are being manipulative. For instance, if you have an insecurity about your share of money , a manipulator will make shameless comments about that topic. Their intentions are to keep you beneath them in order to retain control. If they can retain control, they will feel better about themselves in turn. After all, manipulators have a low self-esteem naturally, and all their tactics are used to fix that.