Men who are financially dependent on their female partners are more likely to cheat than men who contribute equally to the couple's bank account, according to a new study.

But the relationship between male dependency and infidelity disappeared when factors like education, age and relationship satisfaction entered into the mix, suggesting that cheating is a more complex matter than who signs the checks.

The study revealed that men who depend on their wives' or girlfriends' incomes are five times more likely to cheat than men who are not dependent. Women who made much less than their husbands were less likely to stray than women who made more.

"Men and women react very differently to economic dependency," said Christin Munsch, a sociology PhD candidate at Cornell University who is scheduled to present the study today at the annual meeting of the American Sociological Association in Atlanta.

However, Munsch told LiveScience, the results shouldn't be taken to mean that a low-earning man is a cad in training; rather, she said, the findings suggest that economic disparity is just one of many factors that play a role in infidelity.

Cheating Hearts

The study took data from a nationally representative survey of heterosexual couples between the ages of 18 and 28. Each year, the participants in the survey answered questions about their relationships, income and other life circumstances.

Munsch looked at responses from married and cohabitating couples between 2001 and 2007. To find out if people were cheating, she compared three questions: One, whether the person was still in the relationship they'd been in the previous year; two, how many sexual partners the person had had in the past year; and three, if they'd had sex with strangers in the past year. If the relationship was the same but the number of sexual partners was more than one, or if the person had hooked up with a stranger, the respondent was counted as cheating.

The method was very conservative, Munsch said, because it couldn't catch behavior in relationships lasting less than a year. If someone cheating during a six-month relationship, for example, there would be no way to tell from the data, and thus the person would not be counted.

As it turned out, cheating was rare. Only 3.8 percent of men and 1.4 percent of women admitted to infidelity. (Underreporting is a possibility, Munsch said, but no more so in this study than in other surveys of socially unacceptable behavior.) Women became more and more likely to cheat as their income increased in relation to their male partner's. Men, on the other hand, were most likely to cheat if they were economically dependent — or if they made much more money than their female partners. Men who made 25 percent more than their partners were the most faithful.

When it came to high earners, who were more likely to cheat, the findings held true even when age, education level, income, religious attendance and relationship satisfaction were taken into account. For both genders, making more money may lead to more opportunities to cheat, Munsch said. High-paying jobs may require more hours away from home or on the road, for example.

For low-earning men, though, the correlation between cheating and economic dependence vanished when the same variables were held steady. That means that one or more of the variables is affecting the relationship, Munsch said. For example, lower-earning men may be unhappier in their relationships, and that unhappiness prompts them to cheat.

"We don't really know what that causal chain looks like and why it exists," she said. "So that finding needs to be interpreted with caution."

Faithful Mates

One explanation for the finding could be that low-earning men feel that their partners' high wages threaten their masculinity. In this case, the thinking goes, men shore up their ego by cheating. In contrast, low-earning women aren't fighting any cultural stereotypes and may worry about how they'll support themselves if they're caught, so they stay faithful.

"The fact that the relationships are different between economic dependency and infidelity shows that men and women's lives are still not following similar paths when it comes to relationships," said Barbara Risman, the head of the sociology department at the University of Illinois Chicago and the executive officer of the Council on Contemporary Families. "It shows that men are still uncomfortable when they're economically dependent on their wives. That's a very interesting finding." (Risman was not involved in the current study).

But the fact that the relationship between dependency and cheating depends on so many other variables suggests another possibility, said Stephanie Coontz, a professor of history and family studies at The Evergreen State College in Oregon and the author of the upcoming book, "A Strange Stirring: The Feminine Mystique and American Women at the Dawn of the 1960s."

"The relationship between economic dependency and infidelity seems to be concentrated in the outliers — the kind of men who may have married someone they didn't love for mercenary or other reasons, or who may be just too irresponsible or damaged in some ways to earn a decent wage or hold a job," Coontz, who was not involved in the current study, wrote in an e-mail to LiveScience.

"The take-home message for me out of this is more encouraging for women: Yes, there are guys who still take advantage. But if you are married to a guy who doeswork, shares your values and background, is close to the same age, and is a good partner, you should not worry at all if you make more than he does!" Coontz added.

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