<P> The traditional family structure in the United States is considered a family support system involving two married individuals providing care and stability for their biological offspring . However, this two - parent, nuclear family has become less prevalent, and alternative family forms have become more common . The family is created at birth and establishes ties across generations . Those generations, the extended family of aunts, uncles, grandparents, and cousins, can hold significant emotional and economic roles for the nuclear family . </P> <P> Over time, the traditional structure has had to adapt to very influential changes, including divorce and the introduction of single - parent families, teenage pregnancy and unwed mothers, and same - sex marriage, and increased interest in adoption . Social movements such as the feminist movement and the stay - at - home father have contributed to the creation of alternative family forms, generating new versions of the American family . </P> <P> The nuclear family has been considered the "traditional" family since the communist scare in the cold war of the 1950s . The nuclear family consists of a mother, father, and the children . The two - parent nuclear family has become less prevalent, and pre-American and European family forms have become more common . </P> <P> These include same - sex relationships, single - parent households, adopting individuals, and extended family systems living together . The nuclear family is also choosing to have fewer children than in the past . The percentage of married - couple households with children under 18 has declined to 23.5% of all households in 2000 from 25.6% in 1990, and from 45% in 1960 . </P>

Most common type of family in the us