During this time, the girls were also developing preferences in what they played with. Early on, we had been conscientious about providing them with gender-neutral toys like blocks, balls, and puzzles. But as they learned more words, they began to gravitate toward narrative-driven, imaginative play, and became less interested in running and throwing. These predilections corresponded to the kind of research about gender differences in children that I would have dismissed as flawed or irrelevant in my social-constructivist days. In fact, I didn’t need to read any studies to see how misguided I had been—I only needed to watch, at self-segregated parties and preschool, boys the same age as my girls as they wrestled, threw mulch, weaponized inanimate objects, and obsessed over machinery while the girls colored, talked about clothes, and pretended to be families of kitty-cats or ponies.

As soon as my daughters got to the point where they could communicate their desires and feelings, that’s when I could see that there is something more than patriarchy behind the idea that there are “typical” gender differences. I knew that my wife and I had not been rewarding the girls for acting “feminine” and discouraging them from taking interest in “masculine” pursuits. They just liked what they liked, which happened to correspond to what a lot of other little girls liked. Likewise, many of our progressive-minded friends and relatives had little kids who were also developing very gendered interests. The young son of a gentle, peacenik, sports-agnostic couple is a rabid football fan who revels in the violent theater of the gridiron. The daughter of two moms who dressed her in brown until she started caring now wears princess costumes pretty much every day. Of course, not every kid fits neatly into one gender profile or the other; but at least among preschoolers, the differences are very pronounced. And while it’s certainly true that even preschoolers pick up on social cues about gender norms, it’s hard not to believe that there’s something more than peer pressure drawing them to distinctly different areas of interest and activity.