The Pew Charitable Trusts published an interesting study Tuesday on middle-class mobility, looking at the one-third of Americans who fall out of the middle class after growing up there. This chart shows what factors increase the odds of an American being downwardly mobile, the darker bars representing factors that proved statistically significant.

The big takeaway: Divorce and marriage matter, a lot. Education, or lack thereof, is pretty important, too. The picture gets blurrier with drug use: Men who use heroin are more likely to fall out of the middle class, but the effect is statistically insignificant for women. And crack use doesn’t make much of a difference for either gender.

Another interesting finding: While there is an overall gender gap — with more women losing economic ground than men — it’s driven by a disparity among whites. Thirty percent of white women fall out of the middle class, compared to 21 percent of white men. Those figures are nearly equal when you look at both genders among blacks and Hispanics. The Pew study doesn’t explain why this happens, but Pew’s Erin Currier thinks it might have something to do with white women being more likely to scale back work hours when they have children.

“Nothing we looked at in this report can explain that gap,” she says. “You can equalize things like education, marital status, other factors, and it’s still there. But one thing it may be is that white women are more likely to take time off to care for their children. They might be more likely to scale back their work, or work part-time.”