With information available, the genetic and environmental causes of Autism is open to speculation and interpretation.

The [NHS webpage on Autism][1] states (Emphasis mine)

> **Most researchers believe** that certain genes a child inherits from their parents could make them more vulnerable to developing ASD.

> **Cases of ASD have been known to run in families**. For example, younger siblings of children with ASD can also develop the condition, and it's common for identical twins to both develop ASD.

> **No specific genes linked to ASD have been identified**, but it may be a presenting feature of some rare genetic syndromes, including Fragile X syndrome, Williams syndrome and [Angelman syndrome][2].

On environmental causes the NHS say that

> **Some researchers believe** that a person born with a genetic vulnerability to ASD only develops the condition if they're exposed to a specific environmental trigger.

> **Possible triggers** include being born prematurely (before 35 weeks of pregnancy), or being exposed in the womb to alcohol or to certain medication, such as sodium valproate (sometimes used to treat epilepsy during pregnancy).

> **No conclusive evidence has been found** linking pollution or maternal infections in pregnancy with an increased risk of ASD.

Research Autism has some referenced information on [leading research into the causes of Autism][3] from the Medical Research Council, National Autistic Society and the Autism Society of America; and the crux of the matter from what is said here is that the causes are still being investigated and

> There is no known single cause for autism, but it is generally accepted that it is caused by abnormalities in brain structure or function

The site also provides a [list of publications on the **possible** causes of Autism][4]


  [1]: http://www.nhs.uk/Conditions/Autistic-spectrum-disorder/Pages/Causes.aspx
  [2]: http://www.nhs.uk/conditions/angelman-syndrome/Pages/Introduction.aspx
  [3]: http://researchautism.net/autism/causes-of-autism
  [4]: http://researchautism.net/autism/causes-of-autism/publications-on-causes-of-autism