I've read these studies - I have Aspergers, so it is of interest.

As far as I am aware, the heavy metal theory is bourne out of ASD children having substantially higher than normal levels of heavy metal in their hair. It could be a processing heavy metals thing. But is it a cause or an effect? Don't know. I am tempted to go for effect, as cutting heavy metals out of my diet doesn't change things - in fact I'm better (ie less shameful to my mother) with more metals.

Also ASD affects males and females differently: males are easier to diagnose. Although there are more spectrum males, females are still better at hiding it. I'm fairly sure there is more of a genetic link, looking at my family and DH's family. X-linked? Maybe, as it is in my father's family (through his mother) and DH's mother is pretty Aspie too, as is DH.