No one knows exactly what lies at the root of autism — but that hasn’t stopped scientists from speculating. Like the condition itself, the theories of autism are diverse.
Some theories attempt to explain its traits at the level of genes; others look at alterations in brain activity. Still others focus on the psychology of the condition. Two leading theories attempt to explain the skewed sex ratio in autism — why the condition is diagnosed more often in boys.
In this special report, we explain some of the most popular hypotheses of autism’s origins.