Little boys and purple trains. (Cassandra Marcucci)

My first reaction when I found out I was having a boy was, “How could I be growing a penis?” Not only am I the only child of a single mother (who happens to be a former Miss America), but I also attended all-girls’ schools for eight years. On top of that I spend a substantial chunk of my professional life as a sociologist studying femininity in American society.

I then felt fear—not for me, but for my son. A few weeks before discovering the sex the baby I was growing, I completed a book, Playing to Win: Raising Children in a Competitive Culture, in which I write, “Unlike masculinity, multiple forms of femininity are seen as acceptable by parents and by children.” Social scientists continue to find that boys are generally placed into one of three categories: “nerd,” “jock,” or “gay.” Girls more easily move between categories, or create hybrid categories for themselves, like those I label “pink warrior girls.”

How could I create a hybrid masculinity for my son in a world that often asks if you want a “boy toy” or a “girl toy.” Like gender psychologist Christia Spears Brown, author of the recent Parenting Beyond Pink & Blue: How to Raise Your Kids Free of Gender Stereotypes, I didn’t want my son to be weird. I wasn’t trying to make him disavow trains or balls or construction vehicles. But I did want him to be able to pursue anything that interested him even if it was labeled “girl.” This means he’s in a soccer class, but also a dance class; that sitting next to Good Night, Good Night Construction Site on his bookshelf is Pinkalicious.

I needn’t have worried. Carston has managed to create a hybrid gender identity, as he would say, “All by MYself!” He has become my “purple train boy.” The boy saw a train for the first time ever and he was hooked. Score one for a traditional boy interest. However, spending so much time with a traditionally girly mom, he has a deep and abiding love for the color purple. Score one for a traditional girl interest.

One day while playing with a train set, my son declared, “I really, really want a purple train!” I was stumped. I didn’t know if such a toy existed, but we headed to Toys R Us. It was his first time in a toy store, so he was agog as we went up  and down the aisles. I finally asked a sales person if the store sold any purple trains. We were led to the Thomas section.

Sure enough, we purchased Rosie, who was quickly elevated to the top of the hierarchy of our growing train collection. The sociologist in me couldn’t help but notice that Rosie is a female train (though I later discovered that another Thomas friend named “Cheeky Charlie,” one of the few trains with an adjective in front of his name, is also purple).

Based on the look that the sales lady gave us, I know I am an outlier. In her research, Brown finds “it is even less likely that parents of boys would click the ‘girls’ toys’ link to buy a doll, and very rarely would they ever shop the pink aisle at Target, no matter how committed they are to gender equality.”

But if all parents did this with children of both sexes perhaps neither would question whether a boy can be dancer. And, just like parents of girls are encouraged to buy their daughters copies of Rosie Revere, Engineer, so should parents of boys.

I bought that book for my guy because I think it is just as important for him to know girls can be engineers as it is to tell girls that they can be. And at his upcoming 3rd birthday Carston will open the book Iggy Peck, Architect, and something involving his favorite dinosaur, a T-Rex. But I seriously can’t wait to see his face when he opens my favorite gift, his personalized custom “Thomas” engine, a purple boy train I have named simply, “Carston.”

Hilary Levey Friedman is a Harvard sociologist and the book review editor at Brain, Child. You can follow her on Twitter @hleveyfriedman and find links to her work at hilaryleveyfriedman.com.

Like On Parenting on Facebook for more news, essays and advice.

You may also be interested in:

The transgender quandary that wasn’t

Are you raising nice kids? Here are 5 ways to do it

5 things I’ve learned about boys. So far