"We did test to see the affect of children, but it wasn't there," he said. "In other words, in comparing lesbians and heterosexuals who have children, the children don't have impact."
Overall, he said, women's wages tend to be 5 percent less than men's wages, whether single or married.
Lee Badgett, an economist at the University of Massachusetts, Amherst, and the research director at the Williams Institute at UCLA, pointed out that the data about children on wages is murkier than it seems.
"There's the mommy gap for heterosexual women. They earn less clearly when they have kids. But lesbians with kids in their household tend to earn more," Badgett said, citing a study called "The Cost of Parenthood: Unraveling the Effects of Sexual Orientation and Gender on Income," in 2009 by a sociology professor at the University of Houston.
"That's another thing that heterosexual women are being penalized more and, for some reason, lesbians don't seem to have that effect. Is that because of gender roles, maybe? It's hard to interpret the results."
Gary Gates, a demographer with the Williams Institute on Sexual Orientation Law and Public Policy at UCLA, clarified that the higher wages lesbian women tend to receive were specific to older, white women.
"In past research, you don't see a wage premium in younger lesbians or African-American and Latina lesbians," Gates said. "You don't necessarily see non-white lesbian women making more than non-white heterosexual women."
Badgett said there may be interesting differences in the work decisions lesbians make that are resulting in higher wages, but it is unclear what those decisions are and when they take place.
"It's not because employers like hiring lesbians," Badgett said. "Or it's not because they're better bargainers or because they have more empowerment than heterosexual women."
Badgett said the study offered a new perspective because it highlighted that lesbians who had never married earned more than any other female income group.
"It adds to the weight of what a lot of us have thought: There are some differences in decisions that lesbians might make," she said. "You could also look at it to see if they're not as constrained by heterosexual gender roles. Heterosexual women may want to make those choices, too, but, perhaps in the context in their relationships, they can't."
Badgett cautioned that the use of the words "lesbian wage premium" could negate that lesbians are still experiencing prejudice at the workplace, even if their wages are higher than heterosexual women.
"Lesbians still experience discrimination," Badgett added, "as gay men do."