What is the definition of a family today? In order to belong to a family (according to the statistics Norway) the persons must live in the same household. Further the relationship of the members of the household must be one of marriage or of parent(s)/child relationship.
A family then does only constitute persons living together that have a relationship through marriage or of parent/child relationship. I will mention two units where persons live together that do not belong to the definition of a family;
Could be both private and public institutions, however they are usually private households including persons living under the same address and in the same dwelling.