Family comprising parents and children (i.e., not members of the extended family such as grandparents, aunts and uncles). Taken to be the dominant family form in late industrial cultures in which the unit of analysis is the household consisting of mother, father and children. In fact, since the 1970s, this type of family represents a minority of households, at least in Western countries.
See Ecological systems theory, Parenting, Polygynous households