We men say we spend as much time as our partners do on childcare. And we are full of it, say the data. When you actually track how much childcare dads and moms do, the mothers are still shouldering more of the burden.

The basic finding of this report wasn’t much of a surprise to me. We gents start out doing less, from the labor room on into breastfeeding and beyond; that sets up a pattern where moms do more. I’m not proud of this, but if my wife and I did a minute-by-minute inventory of childcare work around the house, I’d come up well short of 50 percent. (Never mind that it certainly feels like I’m on duty every moment.) I work into the evening at least two nights a week, on a schedule that’s not under my control; if those nights go really late, as they sometimes do, my wife will often take the following early-morning shift, too, so I can recover a little lost sleep.

No, the interesting detail to me was that a couple of generations ago, fathers routinely underestimated their time spent raising kids—the opposite of what they do today. Why? Because it used to be stigmatized (“woman’s work” is the phrase that got thrown around). That fascinates me: Not just that mothers used to do the lion’s share of the work but that a dad who changed a diaper was considered a chump. Can you imagine? It sounds as remote as the sixteenth century, at least viewed from our apartment. Yet it was probably true of many of my parents’ contemporaries and friends.

It doesn’t take long to erase even entrenched cultural stigmas anymore. Consider this: When my grandfather saw my kid brother write for the first time, he reacted with agitation, as if he’d seen something dangerous. Why? Because my brother was writing with his left hand. “The devil,” he said. Never mind that in many aspects my Papou was a modern person, one who shopped at Macy’s and liked a glass of Southern Comfort now and then. The way he was raised had determined everything, and he’d been born on a Greek island in 1900. Whereas in our world, four of the past five presidents of the United States have been left-handed. Three decades—one generation—and it’s as remote as Mars.