When it comes to living with a man outside of marriage, daughters often follow the lead of their mothers, according to a new study.

Young adult women whose mothers once cohabited are 57 percent more likely than other women to cohabit themselves, according to a study by researchers at Cornell University and Ohio State University. In addition, such daughters tend to cohabit at earlier ages than others.

"Young women often reproduce the patterns of cohabitation and marital instability of their mothers," said Daniel Lichter, professor of policy analysis and management and director of the Bronfenbrenner Life Course Center, both at Cornell. The study was conducted with sociologist Zhenchao Qian and graduate student Leanna Mellott of Ohio State University while Lichter was a professor at the university. The team's findings were presented Aug. 16 in Philadelphia at the annual meeting of the American Sociological Association.

The likelihood that sons will cohabit is not affected by whether their mothers once lived with a man outside marriage, the study found. But sons are more likely to cohabit if their mothers are divorced or had their first child at an early age.

While a lot of research has looked at how divorce affects children, this is one of few studies on the impact of cohabitation, said Lichter, who pointed out that more than one-third of all births in the United States in 2003 were to unmarried women. More than 40 percent of unmarried cohabiting couples live with their minor children.

The researchers analyzed data from the National Longitudinal Survey of Youth, a nationally representative survey of men and women aged 14 to 22 in 1979 who were interviewed annually from 1979 to 1994, and once every two years from 1996 on.

Mellott noted that the mothers in this study had children at relatively younger ages than the norm and that the sample included more minorities than the general population.

Still, the researchers said that the strong effects of cohabitation on adult children are consistent, even after taking into account factors such as race, education and poverty.

Other results of the study showed that young black men are about 35 percent less likely than white men to report cohabitation, while black women are 90 percent less likely. In addition, higher levels of education are consistently linked to lower levels of living together outside of marriage. While religion itself is not linked to cohabitation, people who regularly attend religious services weekly are much less likely to live together than those who attend rarely or never.

The quality and stability of young adults' relationships are also affected by the stability of their mothers' relationships, the study showed. Each relationship transition for the mothers -- including divorce, widowhood or new cohabitation -- increased the likelihood of cohabitation by 32 percent for their sons and 42 percent for their daughters.

This study is a first step in trying to determine how living together outside marriage may affect children who grow up in such an environment, said Lichter, pointing out that recent estimates suggest that between one-quarter and one-third of all children today will live with cohabiting parents before they reach age 18.

The study was supported in part by the National Institute of Child Health and Human Development.

Adapted from an article written by Jeff Grabmeier of Ohio State University.