Peggy Orenstein’s book “Cinderella Ate my Daughter,” about raising a girl in a culture of Disney and sparkly, was on the New York Times best-seller list. Kylie Jenner was on her way to creating a newer, hyper-femme version of herself with a little army of Kylies to follow.

Articles and psychological reports called for the media to stop oversexualizing and hyperfeminizing young girls. It was time for girls to go back to being tomboys, many adults felt. But was “tomboy” even the right word anymore?

The word “nonbinary” became something people asked the internet about around 2014, making a steady upward climb to present day. Gender identity has become an international conversation, especially among teenagers. In 2017, a University of California, Los Angeles study found that 27 percent (796,000) of California youth between the ages of 12-17 believed they were seen by others as gender nonconforming .

More teenagers overall are identifying with nontraditional gender labels, according to a March 2018 study published in the journal Pediatrics. Some progressive synagogues and Jewish communities are holding nonbinary mitzvahs. Nonbinary teenagers are choosing non-gendered for driver’s licenses.

“When we’re looking at trends that we might see in the community of youth who are identifying as nonbinary, what we really are seeing is a community of people who are just accepting the diversity of gender expression,” said Jeremy Wernick, a clinical assistant professor in the department of child and adolescent psychiatry at N.Y.U. Langone. Mr. Wernick’s work focuses on gender-expansive children and adolescents.

“Yes, nonbinary kiddos are sort of leading the way in pushing the boundaries of those binary stereotypes,” Mr. Wernick said. “But what they’re really doing is modeling for other young people and adults the reality that gender expression can inevitably have an impact on the rest of the world if things are accepted and celebrated.”