No one really knows what causes Autism.  There are many theories.  Some researchers say Autism is caused by environmental factors.  Some believe its linked to early immunizations.  One of the most recent studies suggest that Autism is linked with type 2 Diabetes. It could be a number of reasons. It could be a result of all the chemicals used in food processing and preservatives.  Hormones injected into cows and chickens to keep them alive and to increase their growth. Have you considered the fact that people flush millions and billions of medications in the sewer system on a daily basis!  Not to mention chemicals in the air we breath!