<Table> <Tr> <Td> </Td> <Td> The examples and perspective in this article deal primarily with the United States and do not represent a worldwide view of the subject . You may improve this article, discuss the issue on the talk page, or create a new article, as appropriate . (January 2016) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> The examples and perspective in this article deal primarily with the United States and do not represent a worldwide view of the subject . You may improve this article, discuss the issue on the talk page, or create a new article, as appropriate . (January 2016) (Learn how and when to remove this template message) </Td> </Tr> <P> A nuclear family, elementary family or conjugal family is a family group consisting of two parents and their children (one or more). It is in contrast to a single - parent family, to the larger extended family, and to a family with more than two parents . Nuclear families typically center on a married couple; the nuclear family may have any number of children . There are differences in definition among observers; some definitions allow only biological children that are full - blood siblings, but others allow for a stepparent and any mix of dependent children including stepchildren and adopted children . </P> <P> Family structures of a married couple and their children were present in Western Europe and New England in the 17th century, influenced by church and theocratic governments . With the emergence of proto - industrialization and early capitalism, the nuclear family became a financially viable social unit . The term nuclear family first appeared in the early twentieth century . Alternative definitions have evolved to include family units headed by same - sex parents and perhaps additional adult relatives who take on a cohabiting parental role; in the latter case, it also receives the name of conjugal family . </P>

How many members does a nuclear family have