Money is the root of all evil, as they say, and a couple’s income ratio may serve as a predictor for one of the seven deadly sins — adultery. A new study published in the journal American Sociological Review, has found a consistent pattern in cheating linked to how much money a husband and wife bring home. The more financially dependent you are on your spouse, the more likely you are to cheat on them.

"You would think that people would not want to 'bite the hand that feeds them' so to speak, but that is not what my research shows," the study’s lead author Christin L. Munsch, an assistant sociology professor at the University of Connecticut, in a press release. "Instead, the findings indicate people like feeling relatively equal in their relationships. People don't like to feel dependent on another person."

Munsch studied data collected from 2001 through 2011 on more than 2,750 heterosexual married people between the ages of 18 and 32 years old. She focused on how much each person contributed to their combined total income and then tracked who cheated on who. It turned out that men and women behaved differently depending on who made more money.

When Women Are the Breadwinners

Women bringing home the bacon were more likely to come home to cheating husbands. In an average year, there was a five percent chance a financially dependent woman would cheat on her husband. But men sang to a different tune. When a man was financially dependent on his wife, there was a 15 percent chance he would have an affair.

"Extramarital sex allows men undergoing a masculinity threat — that is not being primary breadwinners, as is culturally expected — to engage in behavior culturally associated with masculinity," Munsch said. "For men, especially young men, the dominant definition of masculinity is scripted in terms of sexual virility and conquest, particularly with respect to multiple sex partners. Thus, engaging in infidelity may be a way of reestablishing threatened masculinity.”

Not only were men more likely to cheat because their ego was at stake, but Munsch also hits on another, more cynical point. Like killing two birds with one stone, the “threatened” man could win back his masculinity while distancing himself, and even punishing, his breadwinning spouse, Munsch explained. Infidelity allowed the man to feel a sense of security at the risk of making the relationship less secure.

The opposite was true for women. When women provided 100 percent of the couple’s total income, they were least likely to cheat. Because women were acutely aware of the ways in which they deviated from societal norms — by making more than their husbands — they were more likely to suffer from increased anxiety and insomnia, and engaged in what psychologists call “deviance neutralization behaviors.”

When women outearn their husbands, they challenge the status quo, Munsch said. It may sound strange at first, but when you take a closer look you’ll see women try to minimize their achievements in order to reinstate their husband’s masculinity for him. Breadwinning wives may also pamper their husbands more by not holding them accountable for housework typically deemed too feminine — all in an effort to keep their relationships intact.

These breadwinning women worry they have taken away one of the defining aspects of what it means to be a man, Munsch said. They work to improve on their husband’s masculinity by becoming more devoted and focused on him, while men tend to seek out their masculinity by playing the field. Munsch was surprised to find the man who makes significantly more than his wife is less likely to cheat, compared to the man who is financially dependent on his wife.

Financial Fidelity: Finding The Perfect Balance

When the scales begin to align and the amount of money men make comes closer to their wives’ contribution, the odds of them cheating decreases. Unfortunately, perfect balance doesn’t mean they’re 50-50. It turns out, a man is least likely to cheat when he contributes 70 percent of the couple’s total income and a woman contributes only 30 percent. However, the heavier the scales tip past that contribution, the more likely it is that he will stray from his marriage.

As soon as a man’s wife is completely financially dependent on him, another kind of mindset feeds a man’s drive to cheat. When men are the breadwinners, they are aware of it, and may assume their wives won’t leave them because of they're dependancy. In cheating, they may also be seeking a partner who aligns closer with the 70-30 income ratio or somewhere near the halfway mark — but without tipping the scale toward the woman's side.

“A husband who earns significantly more than his wife and has an affair — think celebrities, athletes, and politicians — is the type of infidelity that regularly makes front-page news,” Munsch said. "So I wasn't surprised to find that men who make a lot more than their wives are more likely to cheat than men in equal-earning relationships or relationships where they make a little bit more than their wives. But, the affairs of economically dependent men simply don't garner media attention, so we hear about this kind of infidelity far less often."

Source: Munsch CL. Her Support, His Support: Money, Masculinity, And Marital Infidelity. American Sociological Review. 2015.