Why is there an ambition gap between millennial men and women?

Women are outpacing men in education and have been for two decades. They outnumber men on college campuses. They earn more undergraduate degrees. They earn more master’s degrees. They earn more doctoral degrees. For every 100 men who graduate with a college degree this year, 140 women will do the same.

Yet women still make less money and advance in the workplace less often. They are more likely to leave their jobs, especially after having kids. As they age, they face an increased risk of poverty and economic instability.

A new Pew study shows that millennial women (for the purposes of the study, women ages 18 to 32) now make almost as much money as their male peers — a victory insofar as the pay gap is narrower than ever before but disturbing when you consider that even higher educational attainment is not resulting in parity. Women have earned nearly 10 million more college degrees than men over the past two decades, but their average wages remain lower. The shrinking pay gap, too, is not just because women are making more money than they were two decades ago (although they are); it is also because men — and in particular, millennial men — are making less.

The near parity in pay between young men and women disappears as soon as women have children. Kids hamper mom’s earning potential while increasing dad’s. Mothers suffer a wage penalty of about 5 percent per child — and not because mothers work fewer hours or are less committed employees. Rather, it is the very status of being a mother that leads to negative judgments. In one study (PDF), visibly pregnant employees were perceived as “less committed to their jobs, less dependable and less authoritative but warmer, more emotional and more irrational.” Another study (PDF) demonstrated that a female consultant with kids was evaluated as less competent than a female consultant without children.

And then there is the other, perhaps more surprising finding that millennial women do not aspire to the same level of success as their male peers do. Among millennials, 34 percent of women say they have no interest in being the boss someday, compared with 24 percent of men. The reasons behind that ambition gap are no doubt complex, but they likely come down to some combination of 1) men’s being raised with an assumption of authority and an emphasis on leadership as achievement and 2) young women looking at the gender landscape ahead of them and deciding, rationally, that aiming too high would result only in disappointment.

The roots of these differences are both social and political. The biggest impediments to workplace equality — and the easiest ones to solve — require simple legislation. It is a familiar list: adequate paid parental leave, paid sick days, paid vacation, universal health care, a livable minimum wage and state-subsidized, high-quality day care. Those legislative fixes would not simply help women achieve workplace parity; they would help promote a saner balance between work and life, something men report concern about too.

More challenging are the cultural and internal barriers that are less apparent in our day-to-day lives. Women are less likely to ask their bosses for a raise. Even if they do, a boss’s response can often be informed by the societal perception of mothers as distracted or less committed in the office than their male peers. The difficulty is in the invisibility. A boss does not have to be a sexist pig to hold unrecognized biases against women. Women who are not promoted usually have no way to know if the boss would have acted differently if the promotion seeker had been a man. After all, there is always a series of reasons to justify hiring or promoting one individual over another. In one study of lab-assistant hires, those doing the hiring favored applications from men over otherwise identical applications from women. They rated the applicants with male names as more competent and hirable, offered them jobs more often and gave them higher starting salaries. And they always had a gender-neutral reason — this academic achievement, that research experience.

The presumption of male competence and authority runs deep. It attaches itself as soon as we see a male name on a resume, an email or a byline. Because it is so pervasive and tends to crop up in circumstances where many other factors are at play, it is difficult to isolate. The dynamic is hard to see as it happens; the consequences are not.

Women today hold just 4.2 percent of Fortune 500 CEO positions. In the Fortune 1,000, 4.5 percent of CEOs are women. Last month GM hired Mary Barra to head the company, which was good news. But it was news precisely because no woman had ever run an international automobile company before — and because female CEOs are so rare.

I have little doubt that Barra, like other prominent and successful woman before her, will be subject to extensive media critiques of her feminism, her work-life balance, her obligations on behalf of all womankind and her inevitable failure to be everything to every woman (see: Sheryl Sandberg, Michelle Obama, Beyonce). Despite such scrutiny, such women do make a difference. It would be foolish to think that a couple of high-profile hires will fix workplace inequities overnight. The power in having women in corporate leadership roles is not that they are able to swoop in and turn the workplace into a feminist dream. It is, rather, that each of them inches us toward a normalization of female power. Each of them gets us a little more accustomed to seeing female bosses. Each of them gives the others a little more breathing room, a little less weight on her back from shouldering so many expectations. And that proliferation, slowly but surely, is what will quietly shift our internal biases and assumptions about women at all levels of employment.

What happens in the workplace, though, makes up only half of the equation. The other half is what occurs in the home. According to the Pew study, half of working mothers say that having a child made career advancement more difficult. Only 16 percent of working fathers said the same. In fact, having a child helps dads’ careers: Men with children are considered more hirable and are offered higher starting salaries than men without them. Fathers are viewed as both warmer and more competent, and as a society, we harbor long-standing perceptions of dads as families’ primary breadwinners, deserving and needing workplace success. For women, it is the opposite. Single women without children do decently, whereas moms are offered lower salaries and suffer poorer evaluations.

This is not about biology or home commitments trumping work. Yes, women do more around the house than men, but dads are pitching in more than they ever have, especially in the child-care arena. If increased child-care commitments kept parents from working as hard and thereby fairly lowered their pay, you would expect dads to see a parenthood penalty too. But it is only mothers who face such severe challenges after having kids, even when they continue to put in the same number of hours and work just as hard as before. Even looking at parents with similar work experience and qualifications, fathers, despite their increased commitments at home, make more money after having children.

This is not to say that home commitments do not impact work. Mothers are more likely to reduce their hours or take time off from work to care for a child or family member. Forty percent of women with children report having done so, compared with about a quarter of men.

On its face, that sounds like a choice: Women are simply choosing to cut their hours or drop out of the workforce entirely. But those choices are made within a social context. A woman who is heavily involved in the care of her kids is fulfilling her duty. By contrast, a man who is heavily involved in the care of his kids is a hero. Mom watching her kids is mothering. Dad doing the same is baby-sitting. To boot, within the context of a two-parent family, the fact that the female partner is more likely to be paid less helps bolster the logic that she would scale back or quit her job when the kids need her.

Women are getting paid less not just because of individual gender bias. Jobs dominated by women tend to lose status and pay simply because women do them, and wages fall as more women enter an occupation. Take, for example, secretarial positions. A high-status, well-paid job when secretaries were usually men, being a secretary lost prestige and salary when women began to join the ranks in large numbers. Today’s pink-collar jobs are no less inherently valuable than male-dominated labor, but women in these fields are paid far less and accorded less respect. Home health aides, day-care workers, elder-care employees, retail workers and others can expect to put in long, taxing days serving some of the most crucial functions of our economy and are rewarded with a minimum-wage salary that does not come close to covering rent. And they get paid less than their male counterparts — even those men working the exact same jobs.

Workplace parity, then, requires social parity. Such change cannot be legislated in a day, and much of it, in any case, must take place at an individual level. But what is feasible is the passage of legislative solutions to institutional barriers. Maybe, if our federal government values women enough to say that at the most basic level they should have time to give birth and recover without risking financial loss, bosses will follow suit. And who knows? Maybe one day the 10 million women who have more advanced degrees than their male peers will see that translate into something more valuable than a piece of paper.