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Families with one autistic child do have an increased risk of having a second child with the disorder. There are some evidence that hints to genetic factors. F

Families with one autistic child do have an increased risk of having a second child with the disorder. There are some evidence that hints to genetic factors. For example, we know that boys are at much higher risk than girls, but we don't know why. Similarly, we know that older parents are more likely to have autistic children—but again, we don't know why. See https://www.verywell.com/autism-4014759 https://www.verywell.com/autism-4014759

kmonsen 10y ago
This could just as well apply to environmental factors though, siblings probably share those. Also the boy/girl factor could be explained by different behaviors, so different exposures. Not saying I know anything about this, or that this is the case, just that the increased family risk and boy/girl risk doesn't mean it is genetics.
- dsacco 10y ago
  >>This could just as well apply to environmental factors though, siblings probably share those. That's correct, but looking at concordance rates between monozygotic (identical) and dizygotic (fraternal) twins demonstrates that there is at least a partial genetic connection. Identical twins share the diagnosis in 77% of cases, while fraternal twins only share the diagnosis in 31% of cases.[1] Given that identical twins share more genetic material, the conclusion is that autism has a genetic component to its incidence. That said, most research on the subject, including the paper I'm citing, establishes that there is most likely a dual nature-nurture component. In particular, this study was conducted on twins within the same household, so the genetic component would have been augmented by shared environmental factors. [1]: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4440679/ http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4440679/