Family denotes a domestic group of people, or a number of domestic groups linked through descent (demonstrated or stipulated) from a common ancestor, marriage or adoption. A family may be defined specifically as a group of people affiliated by consanguinity, affinity, and co-residence. Although the concept of consanguinity originally referred to relations by blood, many anthropologists argue that the notion of "blood" must be understood metaphorically; some argue that there are many non-Western societies where family is understood through other concepts rather than "blood" from Wikipedia