Not to overdose on folic acid supplements (which I'm sure come with its own slew of problems) but there's a lot of research already done supporting the role folic acid plays in DNA stability, i.e., if you are deprived there will be an increase in rates of mutation of a variety of types (point mutation, whole copy number variants, etc.). And while there is most certainly strong hereditary components to autism over all, that really varies case by case. In the larger studies sampling mutations in autism, particularly the copy number variants, many are inherited from the parents, but a significant portion are also de novo, meaning that they are new mutations arising in the autistic person, either from the egg or sperm or very early in gestation.
I know I'm gonna be raining on peoples' parades here, but genetic stability is heavily affected by environmental interactions. And there are many more ways to mutate the genome than to subject skin cells to UV rays. By targeting and relieving some of the factors that basically help hold the DNA together or work to repair it when mutation inevitably occurs, you can promote characteristic mutations, sometimes even including large segments of DNA jumping around from one location to another. This is actually what a portion of my research focuses on. How the environment not only affects gene expression but how it can also affect the genomic sequence itself. There's a large body of work in these regards although it's not well-disseminated into the popular media. --I think mainly because people don't understand it quite as easily as a concept of a stable genome being the seat of inheritance.
But I recommend looking stuff up on Google Scholar before ya go laughing at reported studies. Not to say there aren't ridiculous studies out there (and, yes, the type that Jenny McCarthy might often jump to support), but don't assume everything that sounds ridiculous is unfounded. There's a lot about biology that'll surprise you.
was it something I said?