Editor's note: Shannon Davis is an associate professor of sociology at George Mason University in Washington. Barbara J. Risman is a professor and head of the Department of Sociology at University of Illinois at Chicago and a senior scholar at the Council on Contemporary Families
(CNN) -- So your daughter will just die if she doesn'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 doesn'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.