Autism in all its ranges is a challenge for the individual and their family. Trying to find out the why of when the human body is different from one individual to the next is frought with peril. Peanuts have been around for thousands of years as a staple food source. Maybe we are better at diagnosising brain abnormalities today, just not that much indication over the years. Love your children and don’t worry about who to blame.
I doubt very much that simply pointing the finger of blame is the issue, I'm sure it's more a question of finding a cure or a method of prevention.
Find out why folks are different, especially when that difference is severe and detrimental enough to be called 'disease', is what medicine is all about. Having no answer is not acceptable when it's your own child. Parents keep looking long after the doctors give up. They make movies about such parents (Lorenzo's Oil).
Some parents are seeing progress under the assumption it's a bacterial cause. You can follow the progress of an Aspergers patient at: Lightomni's progress , going through the Marshall Protocol. It's being used with a strongly autistic child too, but with slower progress: Jason's progress.
Other folks using the MP have noted their allergies and asthma disappear, so there are links between allergies and autism, both may be caused by bacterial infections.