Lately I’ve been seeing some competition between the anti-GMO crowd and the anti-vaccination people as to whose paranoia is more valid. This is because liberals, unlike conservatives, tend to be single hysterical conspiracy believers.
I think the GMO question is still open, although I personally doubt there are any problems with it if done right – we’ve actually been genetically modifying plants for a long time and these are just new methods. Personally I think it’s preferable to pesticide use, which is proven to have deleterious health consequences.
But vaccination is proven to work over a very long time with a very large number of people, and the rate of autism increase does not match the long period of time that vaccinations have been in use.
It does, however, match the time span over which the definition for diagnosis of autism has changed: there are more autistic people because more people are considered to be autistic.
There was a time when autism meant inability to communicate or integrate socially. That’s no longer the case. My mother was a medical worker in autism (she was one of the people who pioneered the use of sign language to communicate with autistic children). When she started in the field there was very little difference between autism and what at the time was called “retardation”. They have since been separated into distinct disabilities, and autism has been broadened to include “functional autism”.