Experts have been grappling with this question for long. The most acceptable answer is that autism is caused by a mix of environmental and genetic factors. The issue is a controversial one and many feel frustrated when they are unable to get a specific answer. Research is going on with funding increasing regularly.

The genetic link to the causes of autism is among the most probable ones. Although, the disease became a diagnosable condition only in 1952, still some families have a history of autism like behaviors. It is also not completely unheard of for a family to have multiple children having been diagnosed with disorders from the autism spectrum, although it is very rare. In such cases experts will have to consider heredity as one of the probable causes.

The next most widely known cause is linked with vaccines and it is also the most debated one also. Several studies have both supporting and contradicting findings regarding vaccines as a cause of autism. The MMR (Mumps, Measles, Rubella) vaccine and Thimerosal, a mercury based preservative used in some vaccines are among the top suspects. In 2007, parents of a child testified before a court that vaccines were responsible for autism in their child.

Environmental factors are also the subject of research as causes of autism. Exposure to toxins, excessive ultrasounds and electronic devices emanating strong electromagnetic waves could be a cause of autism. Numerous studies have been conducted in this regard also.

Besides these causes like bad parenting, atypical development of the brain, food allergies, poor nutrition and Immune deficiency have also been often cited as causes of autism.

But the research conducted so far suggest that autism may be caused due to a combination of several of these factors. Until we get some clear answers it will be better to concentrate more on treatment and support the researchers engaged in learning more about this disease.