Such slippage in support for gender equality may have been a factor in the 2016 election, even though voters 18 to 30 were more likely than any other age group to vote for Hillary Clinton. An analysis of exit polls by Kei Kawashima-Ginsberg of Tufts University reveals that millennial support for a white woman in 2016 was 10 percentage points lower than their vote for a black man in 2008. Furthermore, the gender gap among young people was larger than in previous elections. While 63 percent of young women voted for Mrs. Clinton, only 47 percent of young men did so.

The political scientist Dan Cassino suggests that the increased support for male leadership in home life among 18- to 25-year-olds may reflect an attempt to compensate for men’s loss of dominance in the work world. Youths surveyed in 2014 grew up in the shadow of the financial crisis, which accelerated the longstanding erosion of men’s earning power. During the 2016 primaries, when Professor Cassino asked voters questions designed to remind them that many women now earn more than men, men became less likely to support Mrs. Clinton. Perhaps a segment of youth is reacting to financial setbacks suffered by their fathers. Indeed, a 2015 poll commissioned by MTV found that 27 percent of males aged 14 to 24 felt women’s gains had come at the expense of men.

It’s not just the youngest millennials who seem resistant to continuing the gender revolution. Overall, Americans aged 18 to 34 are less comfortable than their elders with the idea of women holding roles historically held by men. And millennial men are significantly more likely than Gen X or baby boomer men to say that society has already made all the changes needed to create equality in the workplace.

Are we facing a stall or even a turnaround in the movement toward gender equality? That’s a possibility, especially if we continue to pin our hopes on an evolutionary process of generational liberalization. But there is considerable evidence that the decline in support for “nontraditional” domestic arrangements stems from young people witnessing the difficulties experienced by parents in two-earner families. A recent study of 22 European and English-speaking countries found that American parents report the highest levels of unhappiness compared with non-parents, a difference the researchers found is “entirely explained” by the absence of policies supporting work-family balance.