The poll illustrates how dramatically attitudes have changed from the not-so-distant past when the typical family was a married couple with children and virtually every other kind of family was considered abnormal. Today nuclear families make up barely one in five households in the United States, census statistics show. And nearly four in 10 births are to unmarried women, according to the National Center for Health Statistics.
"People aren't embracing these changes, but they are accepting them," said Rich Morin, a senior editor at the Pew Center and author of the report. "The days when people were made to wear a scarlet letter or were shunned after a divorce are ancient history."
The poll asked about 2,700 people their thoughts about seven trends in modern relationships that are upending what used to be considered the traditional family: unmarried parents raising children; gay couples raising children; single mothers; partners living together outside of marriage; working mothers; interracial marriage; and women who never bear children.
The poll results suggest that Americans fall largely into three equally sized camps.
Roughly a third said the trends have no impact on society or are positive. People who were positive about the changing family were overwhelmingly women, Hispanics and East Coast residents who rarely if ever attend religious services.
Another third considered most of the changes harmful to society. The only trends they accepted were interracial marriage and fewer women having children. People who were unhappy with the trajectory tended to be older, white Republicans who are married and religiously observant. They also were more likely to be from the Midwest or South.
The third group tended to accept all the changes except for single motherhood. Virtually all said the growing prevalence of mothers who have no male partners around to help them raise children is bad for society. This group tended to be young, Democratic or independent, and more heavily minority.
With so many different kinds of families in suburban and rural areas as well as in big cities, many people see firsthand the impact on children, Morin added, and consider it mostly positive.
"We see gay and lesbian couples raising children in loving environments," he said. "We see young mothers going off to work and coming home to raise happy, well-adjusted children. Then we see the sometimes tragic consequences of single parenthood, with just one person juggling so many roles."
Andrew Cherlin, a Johns Hopkins University sociologist who studies families, said the Pew poll underscores the widespread acceptance of two-parent families, of almost any ilk.
"Working mothers are acceptable to almost everybody," he said. "Two parents who are unmarried are tolerated or acceptable. But many people, including single parents themselves, question single-parent families. There's still a strong belief that children need two parents."
Cherlin said that for many Americans, the convictions rise not only out of moral concerns but for practical reasons.
"Most people aren't thinking of Murphy Brown," he said. "They're concerned about the economic problems of single mothers, and the amount of effort it takes to be a good parent. People aren't anti-single mother as much as they are pro-two parents."