The study also points to … wait for it … culture, which continues to favor men’s participation in the workforce and women’s participation on the home front. “Current research continues to find evidence of a motherhood penalty for women and of a marriage premium for men,” the report finds. “The greater tendency of men to determine the geographic location of the family continues to be a factor even among highly educated couples.” (The researchers assign minimal importance to theories suggesting that psychological factors such as the notion that men are bigger risk takers, or that women are more averse to tense negotiations have all that much to do with the skill gap.)

“Culture” is kind of a squishy concept. How, precisely, does culture push women’s wages down (or men’s wages up)? They find that one of the more significant contributing factor to pay disparity is due to the fact that women are more likely to spend time away from the workforce and are more likely to work truncated schedules as they try to balance both professional and personal priorities, such as caring for children or parents. Progress in pay parity has been slower among women in highly skilled professions than those in professions that don’t require a college or graduate degree. The paper notes that this may be because women in high-paying, demanding jobs, like doctors or lawyers, are more harshly penalized for time spent away from the office, and clients. Specifically the penalties for time out of the office are high among those with MBAs and JDs.

But it’s also true that these women likely have the option to take more time in the first place. Women with more elite, high-paying jobs typically have better options either via benefits or savings, or family assistance, that can allow them to take time away from the workforce, even if it results in a reduction of overall income.

The researchers note that discrimination, too, can play a role. When it comes to hiring and promotions, concerns that women will (or should) spend more time away from the office, or will somehow underperform can create a labor market where it’s difficult for women to achieve to the most advanced and highly paid positions.