Autism affects about two to three percent of Americans, both children and adults.
With recent reports suggesting that autism rates are rising, often due to improved diagnosis, there is still a lot of confusion and misinformation about what autism is and what causes it.
Decades of research, however, have given us strong evidence about the condition and how best to support autistic people.
Amanda Bakian, Ph.D., an epidemiologist and director of the Utah Registry of Autism and Developmental Disabilities, says the science is clear that genetics play the largest role.
“Autism is a very heritable condition, so it really clusters in families,” she explains. If one child in a family is autistic, the chance of another sibling being autistic is about 20 percent.
Among identical twins, the likelihood rises dramatically, to between 60 and 90 percent.
But that doesn’t mean there is a single “autism gene.” Instead, autism is linked to many different genetic variations scattered throughout human DNA.
Each of these changes is relatively common in the general population and does not cause autism on its own. It is the combination of multiple changes that contributes to whether someone is autistic.
Environmental factors may also influence autism, though their impact is more modest. Conditions that cause inflammation during pregnancy appear to play a role.
For example, if a pregnant person develops a high fever, such as from a COVID infection, their child may have a slightly higher chance of being autistic.
Exposure to heavy metals or air pollution has been linked to similar risks. Still, Bakian emphasizes that these influences are relatively small compared with genetics, and common medications like Tylenol are safe during pregnancy when used to reduce fever.
Research doesn’t just focus on causes. Bakian leads a statewide effort to track autism prevalence through a large database.
This database doesn’t monitor individuals but instead collects information on how common autism is in different communities.
The findings help highlight where autism may be underdiagnosed and where services are most needed. Such research has already helped secure better insurance coverage for autism-related medical care.
Early and accurate diagnosis is especially important because it helps autistic individuals gain access to resources that support their goals.
These may include occupational or physical therapy, applied behavior analysis, or educational programs. The earlier children are identified and connected to services, the better their long-term outcomes tend to be.
When asked whether scientists are searching for a cure, Bakian is clear: they are not—and they should not be.
Autism is not something to be “cured” but something to be understood. Many autistic people view themselves as different rather than disordered and see any attempts at a cure as unnecessary and harmful.
“There’s a lot of strength in being autistic,” Bakian says. “What matters most is helping individuals access the services they need to thrive.”
