Lesbians out-earn their straight counterparts by at least 33 percent, according to a new joint study by the University of Melbourne and San Diego State University.

"Leaning in."

Paper coauthor Nick Drydakis says that lesbians are more skilled at "leaning in" and relaying their value as a result of always knowing they wouldn't participate in a traditional household with a male breadwinner. Lesbians focus on obtaining an education and making significant career decisions, and this ultimately translates into higher earnings, according to the research. A 2013 study by UCLA think tank, the Williams Institute, found that lesbians are more likely to be employed or looking for work than women in heterosexual relationships and that lesbians are also more likely to have a college degree than straight women.

Is the workforce to blame?

The study also points to systemic workforce issues. Mothers are at a financial disadvantage in the workplace because they earn less than those without children. Same-sex couples are also less likely to raise children, according to another recent Williams Institute report, so Drydakis thinks this may give lesbians who aren't parents some professional leverage.

“This might make employers more interested in promoting lesbians, who are less likely to move in and out of the labor market,” Drydakis told news site OZY.

What about gay men?

The same research, however, presents a different scenario for gay men, who are "less likely to be continuously employed than their heterosexual counterparts" and earn around 20 percent less than straight men. This is consistent with 2013 research from the Williams Institute, which found that straight men made $1,000 more in median annual personal income than gay men.

Sheryl Sandberg's wisdom.

Three years ago, "Lean In" founder and Facebook COO Sheryl Sandberg said in a Makers video that women are more likely to do household chores, even if they work full-time, and that it's important to choose a life partner who will shoulder some of the burden of household duties. She added that marrying a woman might even be "better" because that increases the likelihood of having a partner who will help out around the home.

"The most important thing, and I've said it a hundred times and I'll say it a hundred times, if you marry a man, marry the right one," Sandberg said. "If you can marry a woman, that's better because the split between two women in the home is pretty even, the data shows."