Why Your Baby Boy Loves Trucks

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When offered a doll or a toy truck, girls will typically pick the doll and most boys will opt for the truck. But why? Is it something children learn, starting from the moment they're wrapped in a pink or blue receiving blanket? Or could it be that baby boys and baby girls are born with very specific—and gendered—tastes already in place?

The latest research seems to favor the "nature" side of this debate. In two different studies involving monkeys, male adolescent monkeys wanted to play with wheeled vehicles while female monkeys tended to stick with dolls—preferences that monkey society could not have influenced. Taking this research model and applying it to human infants yielded, somewhat surprisingly, very similar results: 3-month-old baby boys preferred looking at trucks and balls and girl infants preferred staring at dolls and other "girl-typical" toys. This "looking data" is striking, says scientists, because it shows that attraction to gendered objects occurs very early in life, before it's likely to have been socialized.

What could possibly be at the root of all this? Hormones. Researchers believe that the amount of testosterone a baby is exposed to in the womb and in infancy correlates with how much time babies spend looking at gender-specific toys. In other words, the higher a baby's exposure to testosterone is early on, the more likely it is for trucks to appeal to him.

As for why it's always trucks and balls versus dolls, the draw of these specific items may come from our ancestors long ago. According to Gerianne Alexander, Ph.D., an author on the "looking data" and a professor of psychology at Texas A&M University, one possibility is that girls have evolved to perceive social stimuli, such as people, as very important (thus the attraction to dolls), while the perceived worth of social stimuli is weaker in boys, who prefer objects that move, a nod to the Paleolithic hunter still hiding in today's male DNA.

What does it all mean for parents? First, no need to toss out that ride-on truck your baby girl seems to adore. "I hope parents recognize that, within each sex, there is considerable variability in toy preferences," Dr. Alexander tells BabyZone.

Moreover, says Dr. Alexander, when given the opportunity, boys and girls typically interact with both dolls and trucks. "The preference only describes which type of toys boys and girls typically interact with most. It seems sensible to provide all children with male-typical, female-typical, and gender-neutral toys—[like] books, puzzles—and simply allow the child to discover what he or she likes best."