Ultimately, the new study finds limited support for the idea that being able to delay gratification leads to better outcomes. Instead, it suggests that the capacity to hold out for a second marshmallow is shaped in large part by a child’s social and economic background—and, in turn, that that background, not the ability to delay gratification, is what’s behind kids’ long-term success.

The marshmallow test isn’t the only experimental study that has recently failed to hold up under closer scrutiny. Some scholars and journalists have gone so far as to suggest that psychology is in the midst of a “replication crisis.” In the case of this new study, specifically, the failure to confirm old assumptions pointed to an important truth: that circumstances matter more in shaping children’s lives than Mischel and his colleagues seemed to appreciate.

This new paper found that among kids whose mothers had a college degree, those who waited for a second marshmallow did no better in the long run—in terms of standardized test scores and mothers’ reports of their children’s behavior—than those who dug right in. Similarly, among kids whose mothers did not have college degrees, those who waited did no better than those who gave in to temptation, once other factors like household income and the child’s home environment at age 3 (evaluated according to a standard research measure that notes, for instance, the number of books that researchers observed in the home and how responsive mothers were to their children in the researchers’ presence) were taken into account. For those kids, self-control alone couldn’t overcome economic and social disadvantages.

The failed replication of the marshmallow test does more than just debunk the earlier notion; it suggests other possible explanations for why poorer kids would be less motivated to wait for that second marshmallow. For them, daily life holds fewer guarantees: There might be food in the pantry today, but there might not be tomorrow, so there is a risk that comes with waiting. And even if their parents promise to buy more of a certain food, sometimes that promise gets broken out of financial necessity.

Meanwhile, for kids who come from households headed by parents who are better educated and earn more money, it’s typically easier to delay gratification: Experience tends to tell them that adults have the resources and financial stability to keep the pantry well stocked. And even if these children don’t delay gratification, they can trust that things will all work out in the end—that even if they don’t get the second marshmallow, they can probably count on their parents to take them out for ice cream instead.

There’s plenty of other research that sheds further light on the class dimension of the marshmallow test. The Harvard economist Sendhil Mullainathan and the Princeton behavioral scientist Eldar Shafir wrote a book in 2013, Scarcity: Why Having Too Little Means So Much, that detailed how poverty can lead people to opt for short-term rather than long-term rewards; the state of not having enough can change the way people think about what’s available now. In other words, a second marshmallow seems irrelevant when a child has reason to believe that the first one might vanish.