A potted family history: notwithstanding the grandmother who yodelled at parties and one addicted to barbituates, our families weren't autistic. All worked, socialised, got on together more or less, and basically functioned.
The biggest mystery of autism isn't the MMR. Our girl never even had that jab. It's why families with no prior history of autism can have severely autistic offspring.
The Health Report's Norman Swan suggested that autism may be a compounded genetic syndrome where like likes like -- that is, slightly autistic-inclined people are attracted to other slightly autistic-inclined people, and together they make one whole autism. Twin studies certainly suggest a genetic link. But gene studies can't explain the apparent rate increase since the 1970s, as most genetic syndromes that inhibit procreation gradually decline out of a population. If it's genetic, why is it on the rise?
Whatever causes autism probably involves up to 30 genes, according to researchers. What's unacknowledged is that many genes rely on environmental circumstances for expression, and certain environmental toxins are gene-altering. The interplay between both makes gene research on its own a blinkered field.
Meanwhile, news reports talk of autism 'triggers', but the image of the loaded gun just waiting to go off is in all likelihood a furphy. Far more accurate would be the metaphor of gas in a coalmine, with our children the canaries. That gas may affect the canaries first, but it sure as hell isn't good for anyone else.
Something causes autism.