For almost 30 years EVERY woman was given pitocin during labor in hospitals, and for about 50-60 years most were. Since we're not a society that is 9:10, or even 1:4 autistic... you can toss that one out the window.
My aunt had totally natural births with both of her children... one of whom is severely autistic (never progressed beyond the age of 2), and the other of whom holds a doctorate of pharmacology.
The "link" between autism and vaccines was debunked YEARS ago in the medical community, the fact that it's finally made the news is an untold relief... HOWEVER for the next several years we're all going to hear that 5, 10, 15 different things "cause" autism. We WANT there to be something that causes it, so we can stop it... but it's not that simple. And unscrupulous people take advantage of parents natural fears to make boatloads of money by coming up with new, wild, and completely unproven (or worse, already disproven) theories by which to capitalize on our fears.
Could pitocin theoretically trigger a genetic "switch"? Possibly. But so could strawberries. Or shampoo. Or a stomach flu. We simply don't know enough yet about genetics to be able to pinpoint *contributing* factors. Picking pitocin as that "trigger" makes just as much sense as picking strawberries. Statistically, as well. How many parents of autistic kids ate or fed them strawberries? OMG... MOST of them!!! Therefore it MUST be strawberries! Wait ALL of them used shampoo!!! It's shampoo!!!
It's hard... because as human beings one of the very first words out of our mouths is "Why?" and we never stop asking it... but sometimes why takes one whole heck of a long time to figure out.