It's an age-old debate of parenting: are boys really drawn to "boy toys" more than girls? Many parents reject this notion, claiming that these types of sex stereotypes are in the minds of parents, and not their children. But a new study may just prove them wrong.

According to a recent article in New Scientist magazine, "exposure to differing levels of hormones in the uterus might sway the preferences that both boys and girls have for "boy-like" toys later on." The article, which details the results of a recent study conducted at Texas A&M University, claims that hormones released both before birth and well into the first few months of life may dictate the type of toys and play that boys are drawn to.

In the Texas A&M study, researchers used eye-tracking software to measure levels of interest in animations of a ball versus a doll and a group of figures versus an individual figure, in 21 boys and 20 girls aged 3 to 4 months. The researchers measured levels of estrogen in the girls' saliva and testosterone in the boys' and compared the lengths of their index and middle fingers — a guide to prenatal testosterone exposure.

The study did not find a link between the girls' behavior and their exposure to prenatal hormone levels. Boys' preferences, however, seemed affected by both, in slightly different ways. According to the New Scientist article, "those with higher circulating levels of testosterone had a stronger preference for the groups of figures over the individuals, while those whose finger lengths indicated that they had been exposed to more testosterone in the uterus showed a more pronounced preference for the bouncing ball over the doll. 

In and of themselves, the results are certainly interesting. But what is really interesting/worrying is that the results would also suggest that aspects of behavior or even gender identity could be altered by exposure to hormone-disrupting chemicals like phthalates or pesticides, both in the womb and early in life.  

Photo: Vinicius Portelinha/Flickr

The opinions expressed by MNN Bloggers and those providing comments are theirs alone, and do not reflect the opinions of While we have reviewed their content to make sure it complies with our Terms and Conditions, MNN is not responsible for the accuracy of any of their information.