What causes Autism is one thing every doctor hears when they tell a parent their child is Autistic. There isn't one definite response to this question. There are lots of thoughts on what causes Autism. A few of the grounds for Autism are believed to be genetic. Physicians think there are many genes that cause Autism, but have yet to locate them. They now think that some individuals are born with the predisposition to be Autistic. Then they have some kind of environmental trigger and they become Autistic.