Of my family, 60% of fathers side show some autistic traits. Of them, around 4 seem to be diagnosable. (There are around 30 that I've met.) Of those I've met on mothers side, she is the only one with strong traits. Now, I am AS, sister is not. Brother, who does not share a father, is possible AS.
Looking at that, I'd have trouble finding the genetic component, as you would assume father's side is the carrier. Yet more children of mothers side show signs. That's the problem researchers are running into. AS and other spectrum disorders follow none of the known inheritance paths.
To answer your question, the likelihood is more than zero and less than one hundred.
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