It seems that autism has the same pattern. It has genetic aspect and environmental aspect and one of personal experience and amount of practice, so no one could identify all the factors, leave alone find a "single cause". Of course, it is genes, for, say 80% (which is rather a flawed mental construct), like it is in everything else - height or IQ, for example (why should it be different?), but the rest 20% are, of course, not mere "air pollution".
It is the same meme-nonsense (with which we're bombarded daily by mainstream media) as to say, "look, children in a toxic environments have worse grades and misbehave more". OK, perhaps they are, but this is an "empty message", a "meme" based on a naive common-sense. Correlation does not imply causation, and even if this factor is a "valid" one, its actual implication is infinitesimally small - it, perhaps, contributes to "stress" or states related to "depression" (which is another meme). Most of these meme-studies are just misuse of statistical tools together with a confirmation and self-serving biases. People construct statistical "evidences" for their own flawed constructs, instead of methodically removing everything "mental" and see what remains.
We should choose the more charitable interpretation, not because there aren't idiots out there, but because doing so leads to more interesting discussion in the long run—and usually in the short run too.
The first question is "How does they manage to properly test this "link" with a distinct control group". Could you explain, please.
So, I prefer to read Simon Baron-Cohen.
If you have specific information about this or relevant research, by all means contribute it. But railing against idiocy in a generic way lowers the signal/noise ratio of the threads: if generic it must be predictable, and if predictable it can add no information. The Principle of Charity is so good for counteracting this that we may add it to the HN guidelines.
Intellectual charity doesn't require accepting anything false. It means that when there are several reasonable interpretations, you should pick the strongest. This goes against the default tendency we all have, to pick the weakest to then have the pleasure of overturning it. That pleasure is strong—so strong that one may begin seeing idiots for it—and it overpowers the pleasures of curiosity, which is what we're going for.