Johnny may be hardwired to play with toy guns and dump trucks after all. As for his little sister's preference for Barbie, chalk it up to DNA, scientists say.
The notion that children's taste in toys might somehow be genetically determined has long been disparaged by psychologists, dismissed as unscientific, sexist or both.
But now a study of rhesus monkeys by U.S. researchers has added new fuel to the nature versus nurture debate.
Published in the journal Hormones and Behaviour, the findings suggest that when it comes to choosing between trucks and cuddly stuffed animals, chromosomes might come into play.
There have been hundreds of studies that sought to distinguish acquired from innate behaviour patterns in small 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 shows - on how little girls and boys should behave, making it impossible to tease the two influences apart.
So a team of scientists led by Kim Wallen, a psychologist at 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.
Most of the animals studied were juvenile - aged between one and four years. "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 by scientists at Texas A&M University, USA. They found that male green vervet monkeys also showed a distinct preference for "masculine" playthings. But Wallen cautions against over-interpreting the results.
He points out that while plush and wheeled categories serve as proxies for feminine and masculine, other toy characteristics, such as size or colour might explain the observed behaviour. - cos