Boys Like Trucks and Girls Like Dolls, but Is It Genetic?

Earlier this month, my son turned two. We didn’t rent a bouncy house or congregate at a kid’s gymnasium; instead we went on a tour of the city recycling center. Forklifts, dump trucks, men in work clothes yelling and hauling crates of bottles and cans onto massive conveyor belts – it was toddler-boy heaven.

Now, I like to think of myself as having taken a gender-neutral stance toward raising my son. Early on, we bought him a stuffed baby doll to encourage empathy and caretaking (he now sings to and sleeps with it every night), and I’m quite proud of his enthusiastic ballet moves. But around the time he turned one, it was like a gene for wheels and motors turned on, as if an obsession with vehicles and machinery was coded into the DNA on his Y chromosome.

And my son isn’t the only one. The more parents I talk to, the more stories I hear of boys’ fire truck fascinations or girls spending hours in ballet slippers enacting the entirety of the Nutcracker. When it comes to our children’s love for stereotypically boy and girl things, clearly something biological is at work.

Are Hormones at Play?

When you see a three-year-old boy pretend machine-gunning his siblings or, as I saw recently at my friend’s house, a five-year-old on a mission to kill ants with a hockey stick in the driveway, a popular conclusion to draw is that they must have higher levels of circulating testosterone.

Not true. According to the well-known author and neuroscientist Lise Eliot, boys and girls have equal hormone levels until puberty. The exception to this is that, in the womb, boy fetuses have a testosterone surge between six weeks from conception and the end of the second trimester, and for a few months after birth, boys and girls have a “mini-puberty,” in which estrogen and testosterone rise. But after six months, it levels off, and doesn’t spike again until the pre-teen years. Interestingly, boy and girl play is similar during these hormonal infant months; it’s actually not until well after the chemicals settle down that the gender play kicks up.

Many scientists, including Eliot, do believe, however, that those early prenatal and infant hormone boosts are enough to wire up little boy and girl brains with slight differences. Early humans obviously didn’t have Tonka trucks, but it might be that the boy brain has a slightly stronger proclivity for high-energy objects that move.

One population that has helped doctors sort out this question is girls with a condition known as congenital adrenal hyperplasia (CAH). Starting in the womb, these babies produce high levels of androgens (male hormones). And even though hormone levels are corrected with supplements after birth, as kids, the girls with CAH tend to be more aggressive and fond of traditionally boy activities. There is no question that, once born, social influences further divide kids into pink and blue camps (studies reveal that parents unconsciously promote stereotypical gender play), but science has shown convincingly that prenatal hormones do play a role.

Gender Identity

But even though my son sometimes seems as male as a junior Chuck Norris, the other day he lifted his shirt and told me he had a baby in his tummy. He declares in the bathtub that he and dad have penises, but every once in awhile I get included in that club as well. That’s because a toddler’s gender identity (the fixed sense we have of our own male or femaleness) is a work in progress – it takes years to establish fully.

By two and a half, most toddlers can correctly tell you which sex they are. And it’s at this point that the explosion of pink princesses and cement mixers hits, even in the most open-minded, gender-equal households. A few of my girlfriends have been thrown by this phenomenon, not considering themselves the “girlie” type and wondering where the insistence on dresses came from. It’s an indication, however, of how little kids see the world in black and white. While they’re still working out the complexities of life, they tend to sort and categorize, making them even more gender-conscious than we are as adults.

So preschoolers know they are boys or girls, but they don’t yet grasp that gender is a constant – a stable trait that will be part of them for life. At this age a boy might still have the belief that he could grow up to be a mommy or that girls have penises when they get older. It’s not until they are six that most children fully own their gender and can wrap their heads around its permanence.

Avoiding Our Own Stereotypes

It’s easy to let the trucks and imaginary guns give you tunnel vision as a parent. When the gender-stereotyped behaviors sprout up, we bring in our own host of preconceived ideas of what it means to be male or female. When you see your son violently colliding trains together, it’s important to remember that he is also a sensitive, emotional, empathetic little person too. He needs just as much for you to quietly read a book, rub his back and ask him how he’s feeling. And when your daughter insists on only pink and tutus, just remember to look out for her competitive, aggressive side as well. She may be destined for math or engineering greatness – it’s just hard to see past the princess costume.

Personally, I’ve embraced my son’s passion for all things on wheels. In fact, I find myself getting excited when I spot one of his favorites. I’ve actually heard myself shout, in genuine enthusiasm, “Look! 18-wheeler!” when we see one pass by. I just try to stay open to the other side of his little personality too. So when we get home, who knows, we may just set the table and have a tea party with our stuffed baby dolls.

Article Posted 8 years Ago

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