12 yr olds

Maybe I'm imagining this, but I have noticed an overwhelming number of parents talking about having children with Autism around the age of 12.
Is there something in our environment (vaccines, food processing, etc.) that changed approximately 12 years ago?
I have also noticed a connection Autism and Military families. I would be intrigued to see data on the number of children with an ASD who were born or raised on or near a military base or that have significant family members (parents, grandparents) that have served in the military.
For instance all 3 of my boys have an ASD, my husband spent 12 yrs in the Navy (10 of which we were on bases) and his father was in the military for 23 years. I personally know of over 2 dozen families with Autistic children (2/3 of the ASD affected families I know!) that have personally served in the military. This seems too many to be a coincidence.
~Michelle

Hello -
You have my attention. Although my husband was not in the millitary both my father and father in law served in WWII in Alaska. What they do have in common is that they both were also volunteer firefighters each for over 35 years.
My husband also recently retired as a volunteer firefighter after 26 yrs.