JOHANNA OLSON-KENNEDY is among the most celebrated youth gender medicine clinicians in the world. She has been the Medical Director of the Center for Transyouth Health and Development at Children’s Hospital Los Angeles (CHLA), one of the first high-profile American youth gender clinics and presently the largest, since 2012. A frequent expert witness in court cases who is often quoted in the media, Dr Olson-Kennedy also leads a $10m initiative funded by the National Institutes of Health to study youth gender medicine—by far the largest such project in America. In addition, she is the president-elect of the United States Professional Association for Transgender Health.