( CNN ) -- So your daughter will just die if she does n't wear a princess costume for Halloween ? And of course it has to be pink . And every little girl you know wants to be a princess for Halloween , except for the neighborhood tomboy down the street ? Is this desire to be a princess hardwired ? Do girls just come that way , wanting to look pretty in pastels ? And does this explain why teenage and adult women are drawn to `` feminine '' careers , and likely to be less competitive in sports and at work than their male counterparts ? That 's what some research scientists think . They argue that differences between boys and girls are in large part because of variations in hormonal levels during gestation , and thus begin before birth . On average , fetuses that become girls are exposed to less testosterone in the womb than those destined to be boys . Lower exposure to testosterone , some scientists claim , makes girls more passive and less adventurous than boys , and more interested in dressing up , looking nice and pleasing others . These scientists admit that some girls embrace a much wider range of interests and behaviors than those that are stereotypically `` feminine . '' But they argue that such girls were exposed to higher levels of testosterone in the womb . The bottom line , according to this school of thought , is that it does n't much matter how parents raise girls . Their paths are predetermined before birth . There 's little point in giving girls gender-neutral toys or encouraging them to think beyond their wedding day . Most girls will naturally gravitate toward pink princess dresses and white wedding dress fantasies , and most women will avoid traditionally `` masculine '' activities and aspirations . We had a unique opportunity to test this theory by analyzing data that followed 342 women for more than three decades , from when they were still in their mother 's womb as fetuses until adulthood . We had measures of how much testosterone each woman had been exposed to in the womb . We also had measures of the kinds of messages the girls had received from their parents . They had answered questionnaires over the years where they described whether their parents had pushed them toward feminine activities or encouraged them to play with a range of toys , including those traditionally viewed as masculine . We found that the level of testosterone exposure in utero did have a small effect on how adult women described their personalities . On average , women exposed to more testosterone reported being less passive and were more likely to exhibit `` go-getter '' personalities . But this only explained about 4 % of the differences in the adult women 's personalities . Far more important , indeed two to three times as important , was what parents had encouraged their daughters to do and be . Women who were more assertive and confident as adults were much more likely to report that their parents had encouraged them to be active and independent . So , by all means , let your daughter be a princess this Halloween if she insists . But also let her know how powerful she looks as a Hunger Games rebel leader , a warrior queen , a pirate captain , or even a ninja , because our research suggests that what you say now will have a powerful effect on the options your daughter will envision for herself later in life . And if she just has to have that pink dress , just remember that less than 100 years ago , many people thought blue was a more appropriate color for girls than pink , because pink was perilously close to red -- a strong , passionate , and yes , masculine color .
Risman , Davis : Are girls hardwired to want pink princess Halloween costumes ? They say some parents say lower testosterone in utero makes girls passive , ` ` girly '' Their own study shows the testosterone has less affect than messages from parents . Davis : Girls encouraged by parents to be independent , active and assertive girls .