A system is a whole made up of interacting parts. While families are composed of individual family members (e.g., mother, father, children), the nature of the family is determined by the interactions between family members. The pattern of interactions among family members creates the structure of the family system. Families are also composed of subsystems, such as the siblings or the parents. Because the family is a system, the members cannot be seen in isolation. If you change one part, you change the other parts as well. Moreover, activity in one part of the system may reflect dynamics in the rest of the system. For example, children may act out at school to force their estranged parents to unite to discipline them.