Yesterday, I bought my almost-5-year-old twin girls their first “big-kid” bikes, complete with chromoly steel frames, 16-inch wheels, coaster brakes, riser bars and knobby tires. Also: pastel pink-and-lavender paint jobs, festooned with hearts and flowers.

I wish I could say that the paint jobs on the bikes were an inescapable product of the hyper-gendered marketing of kids’ toys—which is a real and powerful thing, by the way—and that I had no other options. But the truth is that I could have gotten comparable bikes in green, orange, blue, or any number of gender-fluid colors. At one point, I had half-heartedly directed them to a candy-apple red beach cruiser with flames on the fenders, which I would have ridden with pride at their age (or, like, now), knowing all the while what their response would be. “That’s a boy’s bike,” they sang out in condescending unison, following up with an exchange of the familiar “Daddy is so silly” look.

So they joyfully rode their new pastel bikes around the park for a while, until it was time to go to their first ballet class. Ballet: because every other suggestion for an organized extracurricular activity has inspired responses ranging from tepid to horrified. (Side note: I haven’t pushed them very hard toward organized activities because I firmly believe young children should have plenty of time for unstructured, creative, imaginative play. Also, I am lazy and disorganized.) If you ask my children why they love ballet, they will tell you, “Because it’s beautiful.”

Every time I find myself watching my girls make choices that are stereotypically “girly,” I flash back to a scene just a few years before they were born. I was in graduate school, involved in a lively discussion about the rhetoric of architecture. The details of the conversation are unimportant, but it ended with me appealing to my fellow progressive eggheads, “We all know gender is socially constructed anyway, right?”

I think, at that moment, I actually believed what I had just said. Not just that the notions and valuations of “masculine” and “feminine” were tools of patriarchal oppression; but that all gender differences aside from the obvious physical ones were constructs created and perpetuated, consciously or otherwise, to reinforce social structures.

My belief that gender was socially constructed certainly had more to do with my politics than any review of the science on the matter; but as a childless grad student (and later, adjunct Rhet/Comp professor) married to a brainy, ambitious physician, I found no significant challenges to this element of my worldview.

And then my wife became pregnant with twin girls.

The heaps of gifted and hand-me-down pink frilly clothes and accessories grew far faster than we were able to sort and store them. Bins labeled according to season and size were stuffed, closed, and eventually buried as silky, ruffly, and lacey items with slogans like, “Daddy’s Girl,” “Princess,” and (this was just weird) “Jesus’ Li’l Snugglebunny” continued to pile up. By the time they were born, the room that was supposed to have been their nursery looked like a Komen For The Cure race had thrown up on it.

The profusion of pink paraphernalia only strengthened my resolve to undermine society’s gender messages. I would make parenting into a subversive act by encouraging my girls to be rough-and-tumble, grass-stained, fort-building, frog-chasing, risk-taking, dungaree-wearing, princess-shunning adventurers! But, for the time being, they could wear pink frilly stuff. They were too young to be poisoned by gender norms at that point; and besides, the pink clothes were free.

My wife went back to work when the girls were 4 months old, and I took over the bulk of the daily child care. I began sifting through the clothes to find browns, greens, and reds when I dressed them in the morning, despite my own involuntary “Oh my God, that’s adorable” response to seeing them in pastels. Frills were kept to a minimum, and anything in the clothes piles with the word “Princess” on it ended up in the giveaway box. I wouldn’t let anything—even my own melting heart—distract me from my mission.

There is a stage that usually starts between ages 1 and 2, wherein children begin to develop sartorial sentience. We could call this the “Hell No I’m Not Wearing That” stage.

At 18 months, my daughters started caring about what they wore. A lot. And what they wanted was pink and purple, to the exclusion of every other color. The occasional yellow or red was acceptable, but the suggestion of a blue dress was met with distress, and brown was anathema. For a while, I could get them to wear jeans or shorts with T-shirts; and then they realized that if they screamed enough, I would relent and put them in dresses. Spending time with toddlers is an exercise in choosing battles, and this was one I was willing to concede.

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.

So, I have come around—belatedly—to what everyone else seems to have known forever: that girls and boys have, in general, some different interests, tastes, and aptitudes. Obviously, this doesn’t mean that I’m now going to become a Pageant Dad and discourage my girls from their burgeoning interests in astronomy and paleontology. But my dunderheaded journey from social constructivist to believer that social and biological elements interact to create what we know as gender traits has been valuable. I can see the danger of gender determinism. It’s tempting to get lazy and automatically push girls toward ballet (ahem) and boys toward football, without letting them know that there are other options, and the same goes for academic pursuits. If I hadn’t tried and failed to subvert gender stereotypes in my early parenting, my girls would probably still have the same color bikes and go to the same ballet class; but I might not be teaching them to pound nails and build electrical circuits as well.