[Spellman]

Recommended watching on causes of Autism: https://www.ted.com/talks/wendy_chung_autism_what_we_know_an...

3 major factors that are highly correlated: 1) Using a particular drug 2) Age of father 3) Being male

Majority is genetics though, so if the two parents are both highly intelligent and/or on the spectrum, good chances the child will be as well.

Autism is principally caused by the brain neurons developing too quickly during development, and then not reaching the same levels in fully developed adults. One theory thrown around is it's the rapid neuron development, so having intelligent parents means you have a chance of overshooting the threshold of "safe" development resulting in Autism.

I presume this study has better, more-up-to-date metrics though.

[wbl]

Note that age of father may just be due to delayed mating among broad spectrum phenotype people, and not causally related. We also don't know about the male part for sure because of underdiagnosis among women, but maybe there are X-genes involved? We know some genetic diseases which are X-linked cause autism-like symptoms.