It’s in the Genes
If only the answer to autism were so clear-cut as vaccines. However, there is no difference in autism rates among vaccinated and unvaccinated children. One thing is clear though, and that is that genetics play an overwhelming role in autism. Autism runs in families and studies of twins show that identical twins have up to a 95% chance of both having autistic spectrum disorders compared to less than 25% in fraternal twins. Boys are 4 times more likely to have autism than girls. Several genes corresponding to autism have been identified and more may be discovered.

I have a father who was an aspie, a nephew and a niece who are aspies and a son who is classically autistic. It's in the genes and...
If you check the twin studies you will discover that there are identical twins where one twin is unquestionably autistic and the other is unquestionably normal. There has to be "something in the water".
"Something in the water" is a problem for the pro-vax side. It means that the claim that there is no epidemic is a problem. Epidemics only happen with "something in the water". An autism epidemic also means that the cause of the epidemic has to cover the time span and the geography of the epidemic. An epidemic is a problem for the pro-vax side because there is nothing fill the vacuum left when vaccines are not the cause of the epidemic.
The pro-vax side will only turn aside the autism-vaccine question when they have something else to fill this void.
A previous commenter mentioned "the Dan Olmstead study of Amish children". Olmstead isn't a researcher, he did not perform a study, and didn't really look very hard at the Amish. Dr. Kevin Strauss, MD, a pediatrician at the Clinic for Special Children in Strasberg, PA, has said: “The idea that the Amish do not vaccinate their children is untrue,” says Dr. Kevin Strauss, MD, a pediatrician at the CSC. “We run a weekly vaccination clinic and it’s very busy.” He says Amish vaccinations rates are lower than the general population’s, but younger Amish are more likely to be vaccinated than older generations.
Strauss also sees plenty of Amish children showing symptoms of autism. “Autism isn’t a diagnosis - it’s a description of behavior. We see autistic behaviors along with seizure disorders or mental retardation or a genetic disorder, where the autism is part of a more complicated clinical spectrum.”
source: http://autism-news-beat.com/?p=29
You may not have had an ancestor or a older relative with a diagnosis of autism, but you may have had older relatives who would today have a diagnosis. This is the concept of diagnostic expansion. The quirky uncle, the maiden aunt, the odd greatuncle. Many parents of children with autism today look into their family trees and recognize what would now be called autistic traits in their ancestors.
Phenotype (an individual's observable characteristics) and genotype (the full suite of genetic information) are two separate, but related, things.
A related point has to do with the conditions for handicapped children since (say) the 1950s, and conditions such children as recently as 100 years ago. Perhaps more children with social and tactile difficulties are surviving infancy than was true in 1908.
To me, the genetics studies -- especially the twin studies -- are very compelling evidence.
If only the answer to autism were as clear-cut as bad analysis makes it seem.
However, the Dan Olmstead Survey of Amish Children, the California-Oregon Study of Unvaccinated Children and even the Verstraeten Version 0 study showed vaccinated kids were as much as 11 times more likely to have neurological disorders, including autism.
One thing is clear and that is that some people lack the gene that produces glutathione, which allows the body to excrete mercury. Autism runs in families because they have the same defective glutathione gene, the same eating habits and live in the same polluted areas, using the same poisoned vaccines.
Testosterone makes mercury more toxic, resulting in more autistic boys.
Doctor, in fact autism rates among unvaccinated children have been shown to be significantly lower than among vaccinated cohorts. More studies certainly need to be done but autism rates among the amish and in a clinic having served a large number of children in Chicago have been demonstrated to be much lower than vaccinated populations. Are vaccines the only trigger, no, probably not, but are they a possible contributor, quite possibly. Is there a genetic component -- it is highly likely that there is a subset of our population who are genetically susceptible to toxic environmental insults whether from vaccines or elsewhere. This is not a cut and dried vaccines or genetics argument -- it is far more nuanced and complex.
Where is the study that shows that vaccinated and unvaccinated children have the same incidence rate of autism? If you will read about the informal polls on Amish children you will find that they do not have the rate of autism that other children have. They do not vaccinate!!!!!!!!!!!
When I first talked to my son's pediatrician about the possibility of Autism. He told me it was either genetic or caused by having older parents. Since he was my pediatrician and knew my family history did not contain Autism and my husband's family history does not contain Autism and we were both in our early 20's - it was "impossible" for my son to have Autism. Yet, a few years later, he is diagnosed. Now you have parents with absolutely no experience in disabilities raising a disabled child. If I had known Mercury was in the Vaccines given to my child, I would have never let them touch him, let alone injected them directly into his bloodstream. I also would have started chelation much earlier and would have been able to help my son more. I heard about the vaccines when he was in 5th grade. I started chelating him with a natural supplement. He went from playing in a sand box, to actually WANTING to make friends. Your denial is HURTING children everywhere! Not just Genes!