Is it genetic?

The term genetic keeps coming up. They say autism is genetic. It seems to me everything alive has something to do with genetics, at least loosely speaking. But when it comes right down to it, an affliction is genetic only when one gene is affecting one expression of that gene, and it is expressed or it is not expressed depending on whether it's dominant or recessive. I'll leave it at that even though there is a lot more to it than just that.

Now getting to autism, is it genetic? It is probably genetic, meaning there is a genetic susceptibility. But while brown hair is truly depending on just one gene, autism depends on much more than just one gene. If autism were indeed as solidly tied to just one gene as brown hair is, there would be many more cases of autism because of the Mendelian laws of genetics.

Taking it from there, true autism also is not likely to be passed on within a family because truly autistic people are not likely to have children. But let's say they do. Let's say a mildly autistic person gets married and has children. The children might be mildly autistic or severely autistic. The severely autistic offspring would not be likely to have offspring. That genetic material would not be passed on. Generally survival of the fittest allows offspring with better genes to have a better chance at survival. Because this is so, eventually most severe cases of autism would be eliminated unless there are mutations. That, of course, is quite possible in autism.

In order for mutations to happen in large quantities, there have to be triggering factors. So what are triggering factors? Triggering factors are events or substances in the environment. Toxins such as mercury might be good triggering factors for mutations of genes toward autism. In any case genes do not do it by themselves, and that is all I want to convey this time.