Doctors had told Bo’s parents, and Bo herself once she found out, that her condition was so rare there was no one else like her. But after learning the truth from her medical records, and as she traveled the country telling her story, she found this was untrue. Her California mailbox began to fill with letters from people describing similar experiences.

In 1993, Bo, using the name Cheryl Chase, founded the Intersex Society of North America (ISNA) to meet and help people who, like her, were born with biological sex characteristics that fall outside typical definitions—that is, their chromosomes, gonads, or internal and external sex organs differ in some way from what science and society have long deemed to be “male” or “female.”

ISNA became an eddy of activists, a support group for traumatized people who had more questions than answers, and the birthplace of momentous historical agitations such as “Hermaphrodites with Attitude.” Their mission was to convince the medical establishment to respect intersex people’s rights to health and bodily autonomy by stopping “normalizing” surgeries on children before they were old enough to understand the procedures and consent to them.