Some believe it's environmental factors: exposure to pollution, certain household chemicals, flame retardants on furniture - the list goes on.
Others believe it's directly linked to vaccinations.
But no one has been able to say for sure what causes autism, which is more commonly now called autism spectrum disorders.
One thing is certain, though. Autism is prevalent, and the numbers are shocking. The Center for Disease Control (CDC) now reports that one in 68 U.S. children aged 8 has an autism spectrum disorder.
With numbers that high, it's no wonder people want answers - and the newest study might be able to begin to do just that.
According to research released this week and reported on NBC News, "Autism starts with disrupted genes [and is] a failureRead More »from Autism Starts During Second Trimester, New Study Suggests