The study also found that the proportion of adolescents who were assigned female at birth and have come out as transgender also has not increased, which contradicts claims that adolescents whose birth sex is female are more susceptible to this so-called external influence.

“The hypothesis that transgender and gender diverse youth assigned female at birth identify as transgender due to social contagion does not hold up to scrutiny and should not be used to argue against the provision of gender-affirming medical care for adolescents,” study senior author Dr. Alex S. Keuroghlian, director of the National LGBTQIA+ Health Education Center at the Fenway Institute and the Massachusetts General Hospital Psychiatry Gender Identity Program, said in a statement.

The “social contagion” theory can be traced back to a 2018 paper published in the journal PLOS One. Dr. Lisa Littman, who at the time was a professor of behavioral and social sciences at Brown University, coined the term “rapid onset gender dysphoria,” which she described as adolescents experiencing a conflict between their birth sex and gender identity “suddenly during or after puberty.” These adolescents, she wrote, “would not have met the criteria for gender dysphoria in childhood” and are experiencing dysphoria due to social influence.