I don't think we will ever know all of the causes of autism, there are too many. And of course there are children like my cousin who are diagnosed with Autism even though what he actually has is an unrelated genetic disorder with similar symptoms. But the diagnosis remains because it gets him the services he needs, which is fine.
I can say for certain what caused my son to regress into autism. Vaccines. I think all of them played a roll to some small degree, adding on toxins and mercury, killing off his good intestinal flora, replacing it with ickies (yep that's my medical term for the day
). Then the MMR. Right after that vax he regressed. Like some one threw a switch and my child was gone, replaced with a screaming, non-verbal totally unreasonable clone. He went from verbally advanced to non-verbal overnight. He had these horrible screaming fits. He developed a rash over his entire body (kertosis polaris). He quit eating, he quit sleeping. He quit smiling. MRI showed brain damage caused by swelling, but it had been too long by the time we had the scan to prove what caused the swelling. But even the pedi neurologist said he believes it was the MMR. We have done alot of work to get him back. He isn't fully recoverd, and I don't think he will ever be quite the same. But he is coming back to us. Thanks to the DAN! protocols of biomedical treatment. We treated him for a vaccine reaction and he has responded. That tells me without a doubt that the vax's caused this. Is it the only cause for all children, probably not. Why do some children react and other's don't, I don't know, I have theories, but I just don't know for sure. I just know that ds1 is one of them.