How does family play an important role in the behavior of the child?

It all depends on whether or not the family is around.

If the parents are around they will be a big influence on the child. The child may uncontrollably take on personality traits, behaviors, and attitudes the parents have.

If the family is split up, the child may have torn feelings and make resolutions to never act a certain way.

Overall, the family adds a piece of the puzzle to the child.