And like Mr. Trump praising his daughter’s business acumen, men want different things in their wives than in their daughters. Changing gender roles look less threatening when it’s their children who benefit. According to a survey published by Maria Shriver’s Shriver Report, American men listed “intelligence” as the top quality they valued in both a wife and a daughter, but then the responses split: More men said they wanted their wives to be attractive and sweet than said the same about their female children. For daughters, men ranked being independent, strong and principled as more important qualities than those same characteristics in wives. Two-thirds of men want an independent daughter, but only one in three wants an independent wife. Fourteen percent of men said they wanted a wife who was a homemaker; just 5 percent said the same about their daughters.

This dynamic seems to play out in the Trump family: Mr. Trump’s wife is professionally attractive, anecdotally nice and by her own telling fairly traditional, while his elder daughter is a strong, independent and well-educated businesswoman who was mentored by her father and rose to prominence inside his companies. Ivanka has been more publicly involved in the campaign than her stepmother, serving as something of a surrogate spouse to Mr. Trump by defending his treatment of women and emphasizing his good character. And it is Ivanka, not Ms. Trump, who is slated to introduce Mr. Trump as the Republican Party nominee on Thursday night.

This female empowerment narrative — of the daughter, not the wife — is one Americans are more ready to accept. A man who says he’s never changed a diaper and is on his third marriage to a former model may appeal to a resentful male minority, but will look unfamiliar and unappealing in much of the country. A successful child, though — that’s relatable and desirable. When men have daughters, their attitudes shift and they begin to adhere less stringently to traditional gender roles; no similar effect happens to mothers of girls. Fathers of daughters are also more likely to support reproductive rights than men who don’t have girls.

Men have often given their female offspring more opportunities than their female partners, perhaps seeing their children as extensions of themselves. Even today, many men find themselves newly appalled at sexism after having a girl, a reaction apparently not stoked by being born of a woman, married to a woman or simply seeing women as human. In our reluctantly feminist America, one question this election poses is whether we’ve evolved enough to value women as individuals instead of assessing them relationally, as an attractive wife supporting her husband or as a high-achieving daughter reflecting a flattering light back on her parents.