It’s not just women’s and men’s paths that look different; it’s also how reporters tell their stories. Ms. Gillibrand’s red-district folksiness got her branded by some as “a country bumpkin who is in over her head.” Mr. Buttigieg’s is cast as a bonus — he doesn’t wear a jacket (“I just feel more comfortable with my sleeves rolled up,” he said) and can win in a red state.

Ms. Gillibrand entered the Senate as its youngest member, a designation that was an immediate liability. Although she was at times called a “rising star,” she was caricatured as a clawing Tracy Flick, ambitious but unwilling to pay her dues. Her “aggressiveness seems almost gauche, even for a politician,” a journalist wrote. She was cast as “a young woman in a hurry.”

Few seem worried that Mr. Buttigieg is in a hurry. Instead, people wonder whether America is ready for a millennial president, a question not asked in relation to the admittedly unlikely Tulsi Gabbard, also 37.

Consider too that the years in which one is considered a fresh face or a rising star coincide with the years in which most Americans have children. Mr. O’Rourke, the father of three young children, has spoken (in a tone-deaf way, for which he later apologized) about his wife doing the work at home so that he could be away running for office multiple times. Mr. O’Rourke, who is 46, is cast as young even by his detractors (“ a young man who’s got very little going for himself ,” President Trump grumbled). Does the youthful label come from having young kids? His are 8, 10 and 12. But Ms. Gillibrand also became a parent in her mid-30s, and her sons are 10 and 15.

Trevor Noah was certainly right when he said that at 52, Ms. Gillibrand is not exactly a “young mom.” But since when is a 46-year-old a “young man”? Both of them would be younger than the average American president, who is a touch over 55 — a statistic that includes a great many men born at a time when many people weren’t expected to live much past 40.

While Ms. Gillibrand was called “Senator Working Mom,” Mr. O’Rourke’s status as a parent has been just one part of his story, not the core of it. After losing his Senate race, he took an extended solo road trip to clear his head and blog (or write “in a literary online diary”). A jaunt that would be portrayed as child abandonment had a woman done it “could help him politically, advancing his offbeat brand,” reporters mused. Few fretted about who was watching his children.

Women typically find their family responsibilities to be less flexible. Elizabeth Warren was a young mother and a young law professor at the same time; according to a law school friend, she was also doing all of her family’s shopping, cooking and child care, and nearly dropped out of the work force as a result. One doesn’t imagine a Kerouac-style road trip was on the table for Ms. Warren as a young mom — and certainly not dreams of the presidency. That all came much later, as it does for most women. And later, of course, means older.