Research shows that lesbian women earn more than straight women — even when you control for the facts that lesbian women tend to be¬†better-educated, more likely to be white, live in cities, have fewer children, and more likely to be professionals. So how to explain this wage gap? Economics professor¬†Marina Adshade of¬†Dalhousie University in Halifax, Nova Scotia, examines a hypothesis that it has to do with the division of labor in your typical heterosexual union. In short, the theory goes, a straight woman is raised with the assumption that she will most likely marry a man who earns more than she does for the same amount of work, and also that she will be taking on the lion’s share of at-home, unpaid labor. Which means that she is slightly less motivated that her lesbian peers to get ahead at work. Lesbian women — at least, as long as they have been gay — don’t make this assumption.