Systems theory suggests that families are systems in which individuals are interconnected and interdependent on one another. Thus the understanding of an individual can be analyzed by the prevailing reflection of how the individual's family functions.
In the systems theory, the first of which is that a family is an interconnection of family members. In a family environment, it means that actions by one family member will affect the rest of the members in the family and vice versa. This also suggests that change in one part of the system will reverberate throughout the other parts.
The second feature is that a family is greater than the sum of parts. This means that it would be more accurate to assess an individual by looking at their interactions within the family rather than focusing on the individual's personality as per se. This is because it is believed that individuals are what they are based on their interactions with family members. The start of society begins in each family unit.
Thirdly, it suggests that a family is in equilibrium. This means that the family will generally resist change in such a manner that if any parts within the family tries to change, the rest of the parts in the system will try to pull the individual back to their original state. This is also true even if the change is something positive. However, despite being resistant to changes, the family also constantly adapting itself to its members and the changing environment.
A system can also be flexible or rigid, depending on the boundaries set within a family. Boundary is also a key element of the family system, there can be both emotional and physical boundaries. For families which are flexible, it means that they are "open" and accepts certain changes. On the other hand, a rigid family means that it does not accept any changes at all. In order for a family to function effectively, members should have flexible boundaries, as the family will be in equilibrium without forcing states of change.
Lastly, the system theory suggests that in a family, there are rules and roles made by the family itself and hence, are unique to each and every family. Rules can be spoken or silent and are self regulating within the family. On the other hand, roles are also present in the family, where each individual plays a part in maintaining the family.
A mother who is a vegetarian can possibly influence her family to be more vegetarian even though the other family members may not by their nature, like to eat vegetables. Normally when there is dinner together the whole family had to eat vegetarian meals with her. Over a period of time, the family members individually may develop a habit to vegetables not because they like it, but rather because they are used to it. In this example, the family has open boundaries which potentially save the family from arguments.
All it takes is perhaps the rest of the family to protest to eating vegetarian meals on a constant basis and the mother may stop becoming a vegetarian due to inconvenience and the fear of domestic arguments. When that happens, it is not the mother who does not have the personality to become a vegetarian but rather is forced by the family to dilute away that part of the personality, in order for the family to function well. This phenomenon can be seen in group think as well whereby a group makes a decision not because everybody is readily in for it but rather maybe two dominant characters decide and the rest of the group consent to it.