A nuclear family (sometimes known in the British sociological term, cornflake family) is a household consisting of two married, heterosexual parents and their legal children (siblings), as distinct from the extended family. Whilst the family is a near-universal cultural phenomenon, nuclear families do not form the family unit in every society. Nuclear families are typical in societies where people must be relatively mobile -- such as hunter-gatherers and industrial societies.
Social experiments
A focus of the kibbutz movement in Israel is to raise children communally without any associations with a traditional nuclear family.