FamilyNearly one in three American children live with a parent who is divorced, separated, or never-married. And more people back the view that wedding bells aren’t necessary to have a family.

A study by the Pew Research Center, in association with Time magazine, highlights rapidly changing notions of the American family.

About 39 percent of survey respondents said marriage was becoming obsolete. In 1978, just 28 percent believed so.

About 29 percent of children under 18 now live with a parent or parents who are unwed or no longer married, a fivefold increase from 1960, according to the Pew report being released Thursday.

Broken down further, about 15 percent have parents who are divorced or separated and 14 percent who were never married. Within those two groups, 6 percent have parents who live together and opted to raise them together without getting married.

When asked what constitutes a family, the majority of Americans agree a married couple, with or without children, fits that description. Four of five surveyed included an unmarried couple with children or a single parent. Three of five people said a same-sex couple with children was also a family.

Adults 18-29 are driving the changing views of family. Young adults are more likely than their elders to have an unmarried or divorced parent or friends who do. The survey also found young adults tend to have more liberal attitudes when it comes to spousal roles and living together before marriage.

The Census Bureau recently reported unmarried couples living together increased a sharp 13 percent this year to 7.5 million. Beginning next year, the Census Bureau will publish new, supplemental poverty figures that will broaden the definition of marriage to include unmarried couples, same-sex partners, and foster children who are not related by blood or adoption.

Officials say the measure will reduce the number of families and children considered poor. Currently, unmarried partners who live together with children and work are officially defined as two separate units.

The Associated Press contributed to this report.