Couples who buck tradition and live together without getting married still take on traditional gender roles when it comes to cooking and cleaning, according to new findings from Cornell University.

Cohabitating women do a disproportionate share of the housework, even if they work full-time and the men don't work at all, and even when the women want to share the housework more equally, the researchers say.

"When men aren't working, they don't see domestic labor as a means of contributing," says co-author Sharon Sassler, Cornell professor of policy analysis and management. "In fact, they double down and do less of it, since it challenges their masculinity."

"But when men earn more, women -- who are almost all working, too -- feel obliged to contribute in some way to maintaining the household, generally by cooking and cleaning."

Even when household chores were shared, the women tended to serve as supervisor, she notes. A British study released last March found that women spent three hours a week redoing the chores their men had already done.

Researchers interviewed 30 working-class cohabitating couples between the ages of 19 and 35. Findings, announced Thursday, were published in the journal Qualitative Sociology.