A recent study looks at the gap between men and women's earnings in America. This "gender wage gap" is the cause of ample animosity between those who believe pay differences stem from sexism and those who believe the gap can be explained by differences in men and women's work choices—a false dichotomy if their ever was one (I'll take a-little-of-column-A, a little-of-column-B here, please). Those who believe the gap stems from life choices tend to focus on women taking time off for childrearing and going into less lucrative fields. According to researchers from Indiana and Cornell Universities, the wage gap's persistence can also be attributed to a greater proportion of men working 50 or more hours per week.

"Despite rapid changes in women's educational attainment and continuous labor force experience, convergence in the gender gap in wages slowed in the 1990s and stalled in the 2000s," explain researchers Youngjoo Cha and Kim A. Weeden in their paper's abstract. Looking at data from 1979 to 2000, Cha and Weeden found that while hourly wages overall stagnated during the period, the hourly wage of workers who put in 50 or more hours per week—a practice they describe as "overwork"—actually went up. "Because a greater proportion of men engage in overwork, these changes raised men's wages relative to women's," they write.

It's not merely that more men than women were working 50-hour-plus workweeks but that hourly workers in this category are the only ones who saw their wages rise in the last decades of the 20th century. Kind of a double-whammy of wage gap exacerbation, if you will. Taken together, the increasing prevalence of "overworked" employees, the fact that more men than women fall in this category, and "the rising hourly wage returns to overwork" have magnified the gender wage gap by an estimated 10 percent according to the paper, published in the American Sociological Review.

"This overwork effect was sufficiently large to offset the wage-equalizing effects of the narrowing gender gap in educational attainment and other forms of human capital," the researchers note. The effect was strongest in professional and managerial jobs, "where long work hours are especially common and the norm of overwork is deeply embedded in organizational practices and occupational cultures."

With child care and shuffling still falling much more heavily on women, it's no surprise that less female employees are able to put in 50 or more working hours weekly. And I think this illustrates nicely why the sexism vs choices dichotomy is wrong. Clearly no one is discriminating against women by paying them less for working less hours—there is no central sexist actor here. But there is a subtly sexist view permeating our culture that says caregiving is a gendered job.

Surely many women have zero qualms about being the primary parent; surely many others feel somewhat slighted by the situation. It's impossible to separate gendered choices from gendered disadvantages.

With this in mind, it makes no sense for the government to try and rectify the wage gap administratively because there is literally no way to account for all the contributing variables—such as this overwork one. How could anyone have predicted that hourly wages for "overworkers" would rise while general wages stagnated? How can bureaucrats possibly correct for cultural expectations? Focusing on the wage gap per se will go nowhere near as far toward closing it as focusing on the culture that creates it can.