She has huge eyes, a tiny waist, high cheekbones and fancy dresses. She's everywhere. And she could influence the way your child grows up.

She is, of course, the Disney princess.

Anyone who has heard a toddler screaming "Let It Go" knows the power of America's favorite heroines. Analysts estimate Hasbro's princess-doll empire is worth roughly $500 million. "Frozen" remains the highest grossing animated film of all time.

A new study sought to understand how this sparkly ubiquity shapes preschoolers' attitudes about gender roles and body image. Researchers discovered that it has strong effects not only on girls but also boys. Heavy exposure to Disney princess culture correlated with more female-stereotypical behavior in both sexes a year later. Although that created potentially problematic behavior in girls - relegating them to playing with toys in the "girl aisle" - it had a moderating effect on boys, such as making them more helpful with classmates.

The study of nearly 200 kids found nearly all of them knew about Disney princesses: 96 percent of girls and 87 percent of boys had consumed some form of princess-centric media. Gender differences opened wide, though, when it came to who actually played with the toys. Sixty-one percent of the girls interacted with the merchandise once per week, compared with 4 percent of the boys.

Sarah Coyne, an associate professor of family life at Brigham Young University, asked parents and teachers to report over a one-year period how often a child engaged with princess-related goods. She also wanted to record what types of toys the kids preferred (dolls, tea cups, tool sets, action figures), how they treated others and how they felt about their bodies.

Among girls, higher princess engagement was associated with stronger adherence to stereotypically feminine behavior. In other words, the 3- and 4-year-olds who loved Frozen's Elsa, for example, were more likely to gravitate toward "girly" things, Coyne said. They wanted to play dress-up. They embraced frills. Most of their toys could be found in the "girls" aisle. "A lot of people say: 'So what? We want our girls to be girly,'" Coyne said. "And there's nothing inherently wrong with being feminine. But research has show a strong adherence to female gender stereotypes can be limiting across time."

Girls and women who identify figuratively as "princesses," Coyne said, tend to place a higher importance on appearance. They may forever chase an unattainable beauty ideal, a road that can lead to misery. They might not exert much effort in, say, math class, sabotaging a skill that could have blossomed into a successful engineering career.

Researchers noticed a more subdued effect among boys. Those with higher princess exposure were less likely to shun "girly" things for toy guns. They exhibited more balanced interests, which Coyne predicted will help them relate to others down the road. They also displayed more "prosocial behavior" at home and in the classroom, she said. Boys who watched movies such as "Frozen" or "Cinderella" were more likely to help out at school or share toys.

"Princess media and engagement may provide important models of femininity to young boys, who are typically exposed to hypermasculine media," the researchers wrote. "It may be that boys who engage more with Disney Princesses, while simultaneously being exposed to more androgynous Disney princes, demonstrate more androgyny in early childhood, a trait that has benefits for development throughout the life span."

Neither gender showed signs of lower self-esteem or negative body image. Kids that young, the researchers concluded, generally do not feel self-conscious about their appearance. Coyne wants to interview the same group in five years, she said. Moreover, the majority (87 percent) of the sample was white, while 10 percent was Hispanic and 3 percent was "other." It's tough to say how, say, black or Asian children react to the sea of white faces. It's worth pointing out that Disney princesses have evolved since 1950's "Cinderella" and 1989's "The Little Mermaid." Elsa, for one, didn't wait for a man to come rescue her from a fate of endless winter. (Her sister Anna actually knocked some sense into her.) And the arrow-shooting princess Merida in "Brave" saves a prince from being trapped in the body of a bear for all time.

They're also becoming more racially diverse. The next Disney princess will be 2016's Moana, a Pacific Islander who sets sail to find new land.

But the passiveness embodied by Ariel lingers, Coyne said. The mermaid gave up her literal voice to be with a man, and you can still find her merchandise all over the Disney store.

She does not recommend banning the movie, or any film that doesn't feature a female warrior who saves the day. Her favorite princess is Belle from 1991's "Beauty and the Beast."

"Belle sacrifices herself for her father," Coyne said. "Parents can focus more on her bravery in their conversations with their children, as opposed to glitter and the glam."