Scientific American | A Wong/Getty
Scientific research over the past 30 years has revealed a patchwork of potential causes of autism. Most of them are genetic—the condition is between 60 and 90 percent heritable—and some involve nongenetic risk factors that might impact development during pregnancy. “We’ve found a great deal of the underlying [causes],” says Helen Tager-Flusberg, an autism researcher and a professor emerita at Boston University. But how these different risk factors come together as the brain develops remains a challenge to piece together. “Autism is not a simple disorder,” she says. “There are no simple answers. There are no so-called smoking guns.”