Women who are in same-sex couples and in the labor force tend to make far more money than similar women in heterosexual couples, while men in gay couples tend to make slightly less than their heterosexual counterparts. People in gay couples are also more likely to be in the labor force (that is, working or looking for a job) than their heterosexual counterparts, and they're far more likely to be highly educated.

Those are a few of the datapoints from a new report on the demographics of America's same-sex couples. The Williams Institute, a think tank at UCLA that focuses on LGBT issues, has dissected Census data from 2005 through 2011 to create a detailed picture of the demographics of men and women who live with people of the same sex. And while the economic findings are at first puzzling—why would gay women earn so much money, while men in same-sex homes tend to take an earnings hit?—the author says the principles underlying those conclusions may in fact be nothing new.

Here are a few of the basic economic lessons that the study hits home:

Education pays off.

Among same-sex couples with both partners in the labor force, median household income is significantly higher ($94,000) than among heterosexual couples ($86,000). That's likely due to a number of factors, but education is likely one of them, says Gary Gates, a distinguished scholar at the Williams institute and the study's author. Around 46 percent of people in same-sex couples have college degrees, compared to under one-third of people in heterosexual couples. That higher level of education also likely contributes to higher incomes for same-sex households.

However, Gates points out that there are other factors at work: for example, that among couples, the same-sex population in the labor force has slightly more men than the different-sex population (which is, by definition, 50-50)—and men generally earn more than women.

Having kids changes everything.

Women who are both in same-sex couples and in the labor force make a median of $38,000 each, compared to $30,000 for women in heterosexual couples. That could be an educational effect, but Gates points out that the gap is smaller among young women.

He thinks that the gap could therefore be due to kids. Only around one in five same-sex couples have children under 18, compared to nearly 44 percent of heterosexual couples. Because fewer women in same-sex households are leaving work—even temporarily—to raise children, that could mean greater earnings.

"Many women [with children], they either exit or limit their time in the labor force for a period of time. In the long run, that has an impact," says Gates.

The fact that people—whether men or women—leave the labor force when they have kids also likely contributes to lower labor force participation among heterosexual couples. As of 2011, people in same-sex couples had a labor force participation rate of 82 percent, compared to 69 percent of people in heterosexual couples.

It matters what job you take.

The gap that exists between women living with other women and those living with men is both far smaller and reversed for men. Median income among men who are both in the labor force and in same-sex couples is around $1,000 lower than for men in heterosexual couples. The men in gay couples made $47,000 to the heterosexuals' $48,000.

It is possible that gay men are making less money than heterosexual men because of outright discrimination, says Gates, but he says that a more subtle force may be at work.

"It could be in the form of gay men choosing occupations that are perhaps more accepting but actually pay less," says Gates. "For instance, they can get an office assistant job at the nonprofit that is more accepting than a for-profit."