Last updated: Jan 25, 2017

Hanne Gaby Odiele, a high-fashion model known for her street-style fashion, revealed this week that she was born intersex. “It is very important to me in my life right now to break the taboo,” the 29-year-old from Kortrijk, Belgium, told USA TODAY in an exclusive interview.

So what does it mean to be born intersex? “A person is said to be born with intersex biology when she or he is born with a body that doesn’t fit the medical standards for male or female,” says Alice Dreger, PhD, the founding board chair of the Intersex Society of North America. “There are a few dozen different ways to be born intersex, because sex development is really complicated. It involves genes, hormone receptors, organ development and more,” she says. (Intersex is not about gender identity or sexual orientation.)

Up to 1.7% of the population is born intersex—a figure roughly equivalent to the number of redheads. Odiele has a subtype called androgen insensitivity syndrome (AIS), which means she was born genetically male, but her body was resistant to male hormones called androgens. As a result, she has the physical traits of a woman, but was born with undescended testes.

Odiele had her testes surgically removed at age 10, a traumatic experience that she had trouble understanding at the time. “I knew at one point after the surgery I could not have kids, I was not having my period. I knew something was wrong with me,” she told USA TODAY.

Odiele's experience is not unique. Doctors and parents often choose gender assignment surgery for intersex children, and it's a contentious issue. That's why Odiele is partnering with InterACT Advocates for Intersex Youth, a non-profit organization that aims to stop medically unnecessary treatment on children born with intersex traits.

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“Many of these surgeries are not necessary for the health and well-being of the child,” says Ellen Feder, PhD, a professor of philosophy at American University. Many well-meaning parents are simply uninformed about what it means to be intersex, while in other cases doctors project an inability to love an atypical child onto the parents, explains Feder.

It used to be standard treatment to remove testes in AIS cases because doctors believed leaving them intact increased cancer risk. Today, however, that risk is lower than previously thought and “some [experts] advocate leaving the testes in and letting a woman decide if she wants them out," explains Dreger. "The advantage is that a woman will benefit from the natural hormones of her testes."

Indeed, “doctors have started realizing that the approach they’ve used has resulted in a lot of people feeling they were sexually and medically violated,” says Dreger. “Thirty years into the intersex rights movement, we have yet to hear from anyone who has come out to say, ‘I’m glad my parents chose surgery for me."