For me, someone can be married, but without the presence of children, it s not a family. It s a marriage. Sociologists also make a distinction between the family of orientation, which is the family we grow up in and which gives us a sense of history and identity, versus the family of procreation, which is the family we construct when we raise children. The notion of family ties together these two units as well as the families we inherit when we marry. It yields a sense of belonging and, often, a sense of security.
Family has to do with a sense of connectedness.