What Causes Autism?

Most evidence indicates that the majority of autism cases are of genetic origin. Some are caused by unpredictable genetic errors (called mutations) and others are inherited. Some toxins, like excessive alcohol consumption during pregnancy, can increase risk of autism. Autism can also be caused by infectious diseases during pregnancy, such as German Measles or Mumps. There is no convincing evidence that vaccines specifically cause autism, though it has been known for many years that very rarely, vaccines can cause encephalitis.