A family is a domestic group of people, or a number of domestic groups, typically affiliated by birth or marriage, or by comparable legal relationships including domestic partnership, adoption, surname and in some cases ownership (as was the case in the Roman Empire).
Although many people (including social scientists) have understood familial relationships in terms of "blood," many anthropologists have argued that the notion of "blood" must be understood metaphorically, and in that in many societies family is understood through other concepts rather than "blood."
Article 16(3) of the Universal Declaration of Human Rights says, "The family is the natural and fundamental group unit of society and is entitled to protection by society and the State".
