A nuclear 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. Although, as time progresses, the ideal family image is slowly shifting from the aforementioned to something like that of an amiably divorced couple with joint custody of their children.
Research
Research1 is claimed to show that the nuclear family is better than any alternative arrangement to ensure that members of the next generation obtain the emotional support they need, and help to find occupations. Whilst this may be true, statistics collected by the British government can be used to support the argument that involvement of the extended family might help in keeping nuclear families intact. So whilst the model of the nuclear family might be a good one, increases in numbers of divorced and separated parents mean that many children do not enjoy the advantages that membership of a nuclear family confers on the majority.
Social Experiments
A focus of the kibbutz movement in Israel is to raise children communally without any associations with a traditional nuclear family.
Notes
1. http://www.hewett.norfolk.sch.uk/CURRIC/soc/family/fam2.htm (authorized users only)
See also