Lifestyle preferences vary more from one individual to the next than they do between genders.

Women in the United States earn 57 percent of the bachelor's degrees awarded each year, and 50 percent of bachelor's degrees in science and engineering. They—we—make up close to half of new doctors and dentists. So why are women still so scarce in certain STEM sub-fields such as computer science, engineering, and physics, both at the college level and in the workforce?

Researchers have pointed to many different issues: explicit and implicit bias, work environments hostile to women, internalized stereotypes about women's mathematical abilities, sex differences in cognitive skills and interests, and more. A 2009 study that effectively holds math and science ability constant implies that another dynamic is also at play: On average, men and women—particularly men and women with children— have different lifestyle priorities that make women less likely than men to pursue high-intensity careers in STEM fields.

The study, by Vanderbilt scholars Kimberley Ferriman, David Lubinski, and Camilla P. Benbow, examined the work preferences, lifestyle values, personal views, and life satisfaction of more than 500 young people who, in 1992, were first- and second-year graduate students in the country's top 15 math and science departments. They were surveyed both during graduate school and ten years later (around ages 25 and 35).

For the sake of replicating the findings, the researchers also analyzed the values, views, and life satisfaction of 265 men and 84 women in their mid-thirties with unusual intellectual talents. (This second group was made up of people identified by a talent search twenty years earlier as "representing the top 1 in 10,000 in cognitive abilities.") In short, the study looked not at the preferences and priorities of the general public, but at those of the young men and women capable of extremely high achievement in scientific and mathematical fields.

Many similarities and some differences emerged in work-related preferences. The surveyed graduate students held a lot of preferences in common—for instance, "having the freedom to do their work uninterrupted" was highly prized—and numerous preferences remained stable over time. Other priorities evolved between age 25 and age 35 for both genders: "Leadership opportunities and merit-based pay became more important, while satisfaction, friendships, and enjoyment, at least in the workplace, became less so," Ferriman and her colleagues noted. Certain gender differences were evident at both points in time: "men placed more value on high salaries, taking risks...and the prestige of their organization," for example. Furthermore, and unsurprisingly, parenthood was linked to the work preferences of this group, particularly among women. Most notably, in their mid-thirties, over half of women with children considered working fewer than 50 to 60 hours a week "extremely important," versus less than 20 percent of childless women, childless men, and men with children.

The second half of the study reports on the lifestyle values, personal views, and life satisfaction of both the (former) graduate students and the talent-search participants in their mid-thirties. Once more, men and women shared many characteristics, including similar levels of life satisfaction and career satisfaction. Yet men and women parted company when it came to work-life balance:

Women from both cohorts relative to men placed more importance on part-time work and having a part-time career for a limited period of time, having strong friendships, giving back to the community, and living close to family; conversely, men placed more emphasis on having a full-time career, creating or inventing something that will have an impact, and monetary wealth.

And again, women with children were by far the most likely to desire part-time work:

Almost 40% of women with children in both cohorts reported that having a part-time career was important, very important, or extremely important, while less than 15% of men with children reported that to be true. Moreover, 23% of the graduate student women with children and 38% of the profoundly gifted women with children reported that full-time work was not important to them. In contrast, only 6% of the graduate student men (with and without children) and 15% of the profoundly gifted men agreed.

In this respect, mothers with the ability to achieve prestigious and rewarding careers in STEM fields resemble American mothers in general: Pew Research Center surveys show that close to half of women with children under 18 say their ideal situation would be to work part-time.

One major caveat is in order here. After reporting on the gender differences they discovered, Ferriman, Lubinski, and Benbow emphasized that, in line with earlier research, "The differences observed [in this study] between the genders pale in comparison to the individual differences observed within the genders for both parents and nonparents."

Finally, both men and women, whatever their talents and desires, are apt to find that life involves trade-offs: "Just as a decision in favor of working long hours might lead to greater success in one's career, it might also require sacrifices in one's personal life." I'm all for making parenthood and caregiving more compatible with rewarding careers, but no policy can give us more hours in a day. No one can have it all.