Maybe it’s because I’ve been around autism for so long now, but I can’t understand why anyone would find it so surprising that a possible “cause” of autism is a complex interaction of genes. Several recent stories (such as those documented by Kristina Chew and Mike Stanton) have made this point as if it is some new discovery. Granted, it may have only recently been scientifically validated, but this one seems to me to be common sense.
You might as well ask questions like, “What is the cause of introversion? Extroversion? Natural athletic ability?”
I can hear many people saying something along the lines of, “But those ‘conditions’ are normal.” Are they? I mean, in a statistical sense, are they really ‘normal’? I would say no.
If you look at the introvert/extrovert question, I would guess (yes, I’m guessing, no science here) the bell curve of this spectrum would have a few at either end and the rest (you guessed it) within two standard deviations of the mean. Same for athletic abilities.
If we look at autism in this way, as a spectrum across all people (and not just those we currently refer to as autistic), I propose that we might see something similar. On the left side of the bell curve, you would have those that are very non-autistic, the incredibly sociable communicative, etc etc. On the right side, you would have those that are very autistic (what we now simply call autistic). And in the middle, within two standard deviations, would be the vast majority of us showing our mix of autistic and non-autistic traits.