This is a topic for which long-term data are scarce. And as transgender identities have gained more social acceptance, more parents are faced with questions about whether and how to support their young gender-nonconforming children.

“There’s a lot of public writing focused on the idea that we have no idea which of these gender-nonconforming kids will or will not eventually identify as trans,” says Olson. And if only small proportions do, as some studies have suggested, the argument goes that “they shouldn’t be transitioning.” She disputes that idea. “Our study suggests that it’s not random,” she says. “We can’t say this kid will be trans and this one won’t be, but it’s not that we have no idea!”

“This study provides further credence to guidance that practitioners and other professionals should affirm—rather than question—a child’s assertion of their gender, particularly for those who more strongly identify with their gender,” says Russell Toomey from the University of Arizona, who studies LGBTQ youth and is himself transgender.

(A brief note on terms, since there’s a lot of confusion about them: Some people think that kids who show any kind of gender nonconformity are transgender, while others equate the term with medical treatments such as hormone blockers or reassignment surgeries. Neither definition is right, and medical interventions aren’t even in the cards for young children of the age Olson studied. That’s why, in her study, she uses pronouns as the centerpiece marker of a social transition. Changing them is a significant statement of identity and is often accompanied by a change in hairstyle, clothing, and even names.)

When the 85 gender-nonconforming children first enrolled in Olson’s study, her team administered a series of five tests that asked what toys and clothes they preferred; whether they preferred hanging out with girls or boys; how similar they felt to girls or boys; and which genders they felt they currently were or would be. Together, these markers of identity gave the team a way to quantify each kid’s sense of gender.

The team, including James Rae, now at the University of Massachusetts Amherst, found that children who showed stronger gender nonconformity at this point were more likely to socially transition. So, for example, assigned boys who had the most extreme feminine identities were most likely to be living as girls two years later. This link couldn’t be explained by other factors, such as how liberal the children’s parents were. Instead, the children’s gender identity predicted their social transitions. “I think this wouldn’t surprise parents of trans kids, and my findings are often ‘duh’ findings for them,” says Olson. “It seems pretty intuitive.”

Read: Why is the media so worried about the parents of trans kids?

Charlotte Tate, a psychologist from San Francisco State University, says that this quantitative research supports what she and other transgender scholars have long noted through qualitative work: There really is something distinctive and different about the kids who eventually go on to transition. From interviews with trans people, “one of the most consistent themes is that at some early point, sometimes as early as age 3 to 5, there’s this feeling that the individual is part of another gender group,” Tate says. When told that they’re part of their assigned gender, “they’ll say, ‘No, that’s not right. That doesn’t fit me.’ They have self-knowledge that’s private and that they’re trying to communicate.”