I did a little digging and found that they've found an actual genetic cause for Autism and Aspergers' Syndrome. It seems that it's one specific chromosome that decides to misbehave which causes Spectrum disorders.
From what I understand, this region of the chromosome is swapped with another in Aspergers' and completely missing in those with full-on Autism.
Source:
http://www.nature.com/ejhg/journal/v.../5200939a.html
