How much of our children's gender identity really comes from the way we treat them (outfitting them in pink or blue outfits, showering them with loads of superhero or princess paraphernalia), and how much is straight from nature?

Embracing Masculine & Feminine Traits

Almost from the moment she could reach one tiny hand forward, my daughter, Layla, preferred all things pink and sparkling. Her twin brother, Nolan, veered toward trucks and anything else that beeped or moved. Pretty stereotypical boy and girl behavior -- except when it wasn't. Because my husband, Scott, and I would just as often find Layla building intricate bridges and towers while Nolan strapped on ladybug wings and raced around the apartment pushing a baby stroller.

Five years later, Layla remains the girlie girl, encircling herself with Barbies and bling. Nolan loves to watch his cars speed through the living room and builds imaginative machines with his Tinkertoy set. But the gender and behavior lines are often blurred: Layla is also a complete daredevil on the monkey bars, and Nolan is my biggest helper when it comes to baking. Still, I have to wonder: How much of our children's gender identity really comes from the way we treat them (outfitting them in pink or blue outfits, showering them with loads of superhero or princess paraphernalia), and how much is straight from nature?

Turns out, it's a bit of both. "There are different hardwired tendencies that we see in certain boys and girls, but by far the most potent effect is how we as parents relate to them," says William Pollack, Ph.D., an associate clinical professor in the department of psychology at Harvard University. "We each have our own template for how a boy or girl should act that's largely based on how we ourselves were raised. But the wider the range of acceptable behavior we allow, the more comfortable they will feel as they grow and develop into men and women."

Science shows there are intrinsic differences between boys and girls. But in many ways, we're also very much the same. The key to successful parenting, experts say, is to embrace our kids' feminine and masculine sides.

Difference #1 Boys Like to Move

Right out of the womb, boys tend to be more active than girls. "A baby boy is more likely to look at a mobile held over his crib because he likes the movement and activity," notes Meg Meeker, M.D., a pediatrician and author of Boys Should Be Boys: 7 Secrets to Raising Healthy Sons. "A baby girl will tend to focus on a person's face." As girls grow older, they will often engage in more quiet, sedentary activities. Boys gravitate toward things that move and tend to move around more themselves: this activity might mean that parents of boys need to keep lots of Band-Aids around the house. Research shows that boys are significantly more likely to get injured than girls are, even in the earliest years of life. One Canadian study found that as early as age 1, more than twice as many boys were likely to suffer some sort of injury requiring medical care than girls.

Of course, this difference doesn't hold true for everyone -- about 30 percent of girls are considered "very active" Pollack says. Elaine Yang Wu, of New York City, noticed that about her boy/girl twins early on. "At 6 months, Amelia was doing leg lefts in her crib; by the time she was a toddler, she was wrestling with her brother and rolling around on the floor," says Yang Wu, whose twins are now 6 and who also has a 2-year-old boy. "She's always been very active -- wrestling, digging for bugs, playing sports. She's most natural when she's running around."

Bottom line: Try not to make assumptions about your child's behavior. Be open-minded, so your expectations won't inadvertently limit her potential.

Difference #2: Girls Tend to Hit Milestones Faster

I saw this one firsthand in my house. Layla walked first, spoke first, and mastered the fine art of crayon holding well before Nolan did. That fits with the general tendency for girls to hold themselves up earlier, speak sooner, and have better fine-motor coordination, although both sexes tend to start walking at around the same time. Just look at the drawings in a preschool classroom and you can usually tell the boys' drawings (squiggly lines, lots of motion and energy, but less precision) from the girls' (butterflies, flowers, houses with people). Patience is key here. Judy Marshall, of New York City, mom to 6-year-old Olivia and 3-year-old Jack, says, "Olivia hit all her milestones right on time, so I was surprised that her brother jack wasn't as articulate at an earlier age." Once your child gets older, the developmental difference can carry through to the classroom. "As early as preschool, we start to recognize that boys and girls learn differently," Dr. Meeker says. "Boys may lag behind girls a bit. They have a harder time sitting still and they develop language and fine-motor skills more slowly. Often a boy will be tagged as a slow learner or be labeled with attention deficit disorder when really all he may need is a little time to catch up."

Difference #3: Boys Have Less Fear

Not only are boys more active, but they also seem more willing to take risks, even at a young age. "A girl will see something dangerous, slowly look it over, and sometimes even call attention to it, which may give parents time to intervene," notes Barbara Morrongiello, Ph.D., a psychology professor at the University of Guelph in Ontario. "Boys are more likely to start touching or interacting with a potentially dangerous subject." There's some evidence that this fearless quality is due to hormonal differences, but as parents we also tend to emphasize those distinguishing traits," Morrongiello says. For example: You might tell your son "Don't touch!" when he sees a sharp knife but give your daughter an explanation, like "It can cut you." "Parents may assume that because a girl is more verbal, she'll understsand more than a boy, but it doesn't work like that," Morrongiello says.

Whether you're raising a girl or a boy, every home should be childproofed, even if you think your child won't be able to get into trouble yet. "The challenge is to anticipate the next motor milestone and be on the lookout for it before it occurs," Morrongiello says.

Difference #4: Girls Gravitate Toward Princesses & Anything Pink

Many parents struggle to shield their offspring from the boy-versus-girl marketing onslaught. I know that when Layla was a baby, I swore she wouldn't get all the princess paraphernalia. But soon enough she inherited her older cousin's cast-off gear and started tottering around the house in light-up plastic pumps and a glittering Sleeping Beauty dress.

While you can try to avoid gender-typing your little one's toys, you might be fighting Mother Nature. A 2009 study from Texas A&M University found, using eye-tracking technology, that by as early as 3 months, girls and boys show a visual preference for traditionally gender-specific toys such as dolls or trucks.

So whether or not you outfit your daughter head to toe in princess garb or give your son a plastic sword to do battle, there's a good chance they'll get that exposure on the playground or in day care. "Girls, especially, seem to go through a phase where they're intensely interested in girlie things, like wearing a fairy costume everywhere they go," says Kristina Zosulus, Ph.D., an assistant research professor at Arizona State University's School of Social and Family Dynamics in Tempe. "Some parents encourage it; others think it's just plain crazy. But often the child is going to gravitate toward it one way or the other. It's just a way of developing a gender identity."

The same idea holds with boyish behavior. "You can give your 18-month-old son a doll to teach him to be more nurturing, but don't be upset if he rips off its head," Dr. Meeker adds. "He's not being violent: He just may need to build and tear down, which is why blocks and big motor toys tend to be more popular among boys."

Don't forget that many toys aren't necessarily gender-specific. In one recent study from Arizona State University, researchers found that the most popular toys among toddlers weren't the typically girlie or boyish items, but neutral ones such as nesting cups and building blocks. "Expose your child to as many things as possible, and see which ones he hooks onto," says Michael Thompson, Ph.D., a child psychologist outside of Boston. That worked for Jeanne Coffey, of Nahant, Massachusetts. "At 21 months, Lila's favorite thing is big trucks," she says. "Her favorite day of the week is when the garbageman comes, but she also likes to wear necklaces and put her baby doll down for a nap. We're comfortable letting her play with whatever she wants."

Questioning Gender

Our friend Tyler, 5, has always loved the color pink. And he's told his parents on more than one occasion that he'd like to be a girl. "We try to take it in stride," says his mother, Corey. "He'll either grow out of it -- or he won't -- and we occasionally try to gently guide him to more traditional boy stuff, but usually we just let him be himself." That's a good approach, says Michael Thompson, Ph.D., a psychologist specializing in children and families and coauthor of Raising Cain: Protecting the Emotional Life of Boys. "Childhood play doesn't necessarily predict adult behavior. If you let your child do his thing, within reason, you're going to help him develop into a healthy adult."

Still, many parents wonder. If a boy plays with dolls and likes to tromp around in his mother's heels, will he be gay? You can ask the same question if a girl can't stand to wear a dress or prefers pirates over princesses. Most experts say that only time will tell. "We tend to read too much into our kids' behaviors," says pediatrician Meg Meeker. "Kids need the opportunity to explore different dimensions of their character. Ultimately, they're going to be who they are -- there's not a lot you can do about it."

Originally published in the April 2010 issue of American Baby magazine.

American Baby