The overlap is increasingly difficult to dispute. Explaining why it exists is the harder scientific problem.

For years, researchers noticed an unusual pattern in clinical settings.

Autistic people appeared unusually likely to report gender diversity.

Transgender and gender-diverse people, in turn, appeared unusually likely to be autistic or to score highly on measures associated with autism.

At first, there was an obvious concern.

Clinics are unusual places.

People who reach specialized services are not random samples of the wider population. Referral practices, diagnostic patterns, and access to care can create associations that look much larger than they really are.

So researchers looked elsewhere.

The association remained.

It appeared in community datasets, nationwide administrative records, systematic reviews, meta-analysis, longitudinal research, and clinically characterized samples.

At this point, the central scientific question has changed.

The interesting question is no longer simply whether autism and gender diversity overlap.

They do.

The question is why.