“The big growth in childbearing outside of marriage we’ve seen over the past few decades is not among the poor and it’s certainly not among the college educated,” says Johns Hopkins university sociologist Andrew J. Cherlin. “It’s among people in the middle, the high school educated 20-somethings. Those are the ones who have changed their behavior the most.”

In a new study, Cherlin and his co-authors looked at the life patterns of 9,000 millennials and found that those who lived in the areas with the least access to what he calls middle order jobs — those that do not require a degree but provide a living wage, such as manufacturing — were the most likely to have kids before they got married.

In practice, these were also the areas with the greatest income inequality. So while it’s true that income inequality is changing the way millennials start a family, it’s not because of the increasing gap between rich and poor. It’s because people don’t want to get married if they don’t have a steady income and a stable work situation.