Once primarily limited to severely disabled people, autism began to be viewed as a spectrum that included children and adults far less impaired. Along the way, the disorder also became an identity, embraced by college graduates and even by some of the world’s most successful people, like Elon Musk and Bill Gates.

Health Secretary Robert F. Kennedy Jr. has called the steep rise in autism cases “an epidemic.” He blames theories of causality that mainstream scientists reject — like vaccines and, more recently, Tylenol — and has instructed the C.D.C. to abandon its longstanding position that vaccines do not cause autism.

Today, Azeen Ghorayshi explains what’s really driving the increase in diagnoses.

Guest: Azeen Ghorayshi, a science reporter for The New York Times.

Background reading: Should the autism spectrum be split apart? There are no easy answers for parents of children with autism.

Photo: Eric Gay/Associated Press

For more information on today’s episode, visit nytimes.com/thedaily. Transcripts of each episode will be made available by the next workday.

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