The evidence continues to provoke and confound. The consensus from a group of studies concluded in the past six months is "both". But it's not as simple as that. Let's break it apart.
There is the multiplex version of autism (parents have multiple children with autism) in which several genes are affected. This is the inherited type of autism.
The simplex version (parents have a single child with autism) breaks down into three types (but stay tuned, this will explode into a multitude of types very soon). First there are some rare inheritable disorders such as Rhett's and Fragile-X. These make up 8% of the multiplex type. Next there is a genetic version which is typically caused by mutated genes from aging parents. This is not inherited, but is still genetic. This, too, accounts for only 8% of the simplex cases. What is left is a whopping 80+% of cases are not related to genetics. We used to think that autism 90% was genetic. One researcher called this new finding, "humbling".
As we all learned in biology, the environment of the mother's womb is instrumental in a baby's development. Researchers are now looking at the second trimester of pregnancy as being the key time that disruptions in development may occur. And high on the list of what they are looking at is a disruption of RNA functionality. RNA decodes the DNA strands in the body. If RNA is not performing its jobs correctly, huge changes can occur in the development of the child.
And now we come back to the miracle "cures" achieved with food supplements, changes in diet, hyper-oxygenation, etc. Is there a problem in specific children with the specific RNA mechanisms that ultimately create the proteins needed for food digestion, toxin removal and oxygenation? What is it about these remedies that affects not just the gastric system (for example), but affects the child's ability to communicate and to interact socially?
We also come back to the question: "What is autism and what are it's causes?" Will we continue to define it as a collection of symptoms: lack of social interaction, delayed/disrupted communication skills, etc.? Or will we define it in medical terms by the mechanisms that cause it. Stay tuned!
NIMH. (2011, 6 28). Autism Spring. Retrieved 10 31, 2011, from National Institute of Mental Health: http://www.nimh.nih.gov/about/director/2011/autism-spring.shtml