There is no way to say this other than there is a subset of the population that is genetically predisposed to be environmentally injured. Mast cells are another flag. Its a chicken/egg discussion tho - do the increased mast cells come before the injury or are they a result of the injury. And why aren't we screening for this?
The Autism community knew about this 5+ years ago. I wrote a blog in which I mentioned it... We went on one of our better tolerated supplements as a result of that - neuroprotek. We had to stop it a while later as it became cost prohibitive to use the amount required.