I think the problem here is conditions which induce similar symptoms to autism, and are caused by external factors, being misidentified as the same type of brain development variations which are actually the cause of autism.
You can exhibit autistic traits due to a toxic reaction from some environmental factor, and those traits could possibly be curable, but you weren't actually autistic if your brain structure was not altered during your pre-natal, and post-natal development by said chemicals.
My mother suffered from Toxemia during her pregnancy with me, caused by the water pipes in Denton County becoming contaminated and leeching salt into the drinking water.
Numerous women were affected by this at the same period, and I can definitely state that my sternum being "pigeon chested" is a result of it impairing my bone calcification while I developed.
There were numerous children in school with me who also had mothers that suffered from this, yet I can honestly say that I never met someone who I was certain had the same type of wiring I did, though there are a couple of friends that exhibited semi-autistic traits, I've universally been disconnected on a different level than they were.
Were there a huge number of autistic children born in Denton County in the 1980's, I am sure I would have learned what Asperger's is before I did, I would probably have been diagnosed due to the condition showing up enough for people to take notice of the "similar differences" we exhibit among a wide sample of children in the same grade.
As it was, I was just a really really smart kid who never quite "got" some really simple things, and as such spent lots of time bucking against the system which everyone just expected me to fit in naturally.
I do however see aspects of Aspie traits in my mom, her uncle, her mother, my great grandmother on my dads side, to various degrees. I suspect that the only man I ever felt a truly paternal love from/towards, my dads grandfather, was on the spectrum. We identified with each other immediately, in a different way from our other relatives, and I was always as fascinated by the termites eating the rotten tree by the garden as he was. He was a 70 year old kid, and I cried when he died the same way I cry for my cats.