Johnny may be hardwired to play with toy guns and dump trucks after all. As for his little sister's preference for Barbie and Beanie Babies, chalk it up to DNA, say scientists.
The notion that children's taste in toys might somehow be genetically determined has long been disparaged by psychologists, pooh-poohed as unscientific and sexist, or both.
Read more: Babies choose gender-specific toys
But a study by researchers in the United States has added new fuel to the nature versus nurture debate, and suggests that when it comes to choosing between trucks and cuddly stuffed animals, chromosomes could make a difference.
There have been hundreds of studies that sought to distinguish acquired from innate behaviour patterns in small children.
Read more: Gender stereotyping children
But by the time kids are old enough to choose and play with toys, they have also been socialised - picking up cues from their parents, peers and television - on how little girls and boys should behave, making it impossible to tease the two influences apart.
Monkeys not subject to advertising
So a team of scientists led by Kim Wallen of the Yerkes national Primate Research Centre in Atlanta, Georgia decided to offer typical "male" and "female" toys to rhesus monkeys to see if preferences aligned with sex.
Much to their surprise, they did. The 11 male monkeys headed straight for the wheeled toys, such as dump trucks, leaving the plush toys more or less unmolested. The 23 females were more curious, and played with both.
"They are not subject to advertising. They are not subject to parental encouragement, they are not subject to peer chastisement," said Wallen.
The results support an earlier study at Texas A&M University, with green vervet monkeys, which also showed a distinct preference among male monkeys for "masculine" playthings.
Wallen's study was first published in the journal Hormones and Behaviour, and reported on the British website NewScientist.com. – (Sapa-AFP)
Gender identity and socialisation
(April 2008, updated 2014)