Local governments are increasingly promoting mixed-income housing as a tool for fighting poverty, on the assumption that economic integration gives low-income children a better chance at overcoming poverty. New York City Mayor Bill De Blasio, for instance, has set a target of building 200,000 affordable housing units in the city, and he wants them to be distributed throughout mixed-income and more affluent neighborhoods. “Our goal is really to foster more economically diverse neighborhoods,” Alicia Glen, Deputy Mayor for Housing and Economic Development, told the New York Times.

These programs rest on the assumption that mixed-income communities benefit low-income residents. Poorer children might profit from access to better neighborhood schools and facilities; the aspirations of their better-off, more future-oriented peers might rub off on them. Such a housing policy seems especially attractive when you consider that a child born into a low-income neighborhood has a 64 percent chance of moving down the socioeconomic ladder over the course of his life. Low-income neighborhoods suffer from higher crime rates, lower educational attainment, and poorer health; recent research even found a connection between growing up in a poor neighborhood and PTSD.

But a new paper in the Journal of Child Psychology and Psychiatry suggests that mixed-income housing has its own problems, too. A team of researchers at Duke University found that low-income boys in mixed-income communities are more likely than their peers in uniformly poor neighborhoods to engage in anti-social behavior such as fighting, lying, and stealing. The greater the economic inequality in the neighborhood, the worse the low-income boys in this study fared.

Candice Odgers, a psychologist and researcher at Duke’s Center for Child and Family Policy, and her team analyzed data on 2,232 children in England and Wales, following them from birth until the age of 12. They used Google Street View to assess the conditions of public facilities and parks in the children’s neighborhoods, sent researchers to conduct in-home assessments with their families, surveyed kids’ teachers on their behavior and interviewed their neighbors about their communities.

“Our initial thought was that low-income children growing up alongside more affluent neighbors would do better than their peers growing up in concentrations of poverty,” says Odgers. “What we found was really surprising: The low-income boys who grew up in more affluent neighborhoods actually engage in more anti-social behavior than their peers living in very high-poverty neighborhoods.”

This effect didn’t seem to apply to girls; the researchers hypothesize that boys are more influenced by their neighbors because they spend more time outside in the community. “Parents living in high-risk neighborhoods tend to monitor their girls more closely than their boys,” says Odgers. “Boys, who spend more time in public places, might have more exposure to violence in the neighborhood.”

This isn’t the first study to cast doubt on mixed-income housing policies. In the 1990s, the U.S. Department of Housing and Urban Development sponsored an experiment called the “Moving to Opportunity Study”: researchers offered thousands of low-income families vouchers in exchange for moving to more affluent neighborhoods. Boys—but not girls—who relocated were more likely to suffer poor mental health, including “conduct disorder.”

According to one theory, low-income kids in mixed neighborhoods commit more crimes like theft because the temptation is greater; they have access to more affluent targets. Odgers prefers the “social position hypothesis”: Children judge themselves in relation to their peers, and poorer kids may feel insecure and act out if they’re surrounded by kids with way more resources. “Growing up in the shadow of wealth is going to feel very different. It’s going to affect how they view their opportunities, their ability to get ahead.” And feelings of competition or social distance could make the whole community less cohesive; in a uniformly low-income neighborhood, “There might be an opportunity to develop stronger social bonds,” says Odgers.

Behavior is only one metric of success. Odgers’s next study will compare the educational outcomes of children in different types of neighborhoods. In the meantime, she cautions against seeing mixed neighborhoods as a panacea. “Concentrated poverty is a toxic environment,” she says. “But simply creating an economically mixed community is not likely to solve the problem on its own.”