Is autism and Asperger's syndrome caused by genetics or some other factor such as the environment?

I am aware about the Neanderthal Theory of autism, Asperger and ADHD, but am not interested in this due to it appearing too broad and to me seems based off of opinions like preferring the cold to the heat which is not always the case, a the term "lack of social life" seem's very broad and not clear nor specific in the aspects of socializing that they are not good with. The aspect of having big brains is also very broad and does not cover in any detail about what it means by that, however if it means intelligence then this is a development from back when we needed to hunt for food as we started to create things and fleeing particular pray on sight became instinct. The section about being meat eaters does not conclude anything as many autistic people are vegans the same as neurotypicals so does not lead us anywhere. The section about woman being more submissive sexually is also not conclusive as most autistic people are asexual so there is no real dominance by both genders as most do not even partake in sexual activities. The graphs included are also questionable as they all seem to be in favor for aspies as they score higher on everything which i would say for things like the chances of having OCD they would be very much correct as the chances of having this when on the spectrum is 40 times more likely. A lack of organization is mentioned which to me does not seem right i feel that we over plan and organize. These category's specified do not cover everyone on the spectrum so therefore is not conclusive.


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

The NHS webpage on Autism 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.

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 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

  • $\begingroup$ thanks for the answer that's interesting and until i physically look into it a lot more i wont know exactly how it is developed. i mean the reason i think its genetics is because of it running in my family appearing to get less mild as we go down the generations so from nothing in my parents to me with Asperger's syndrome, then my sister who is slightly further along the spectrum, then my brother who is the furthest of us along the spectrum, this is also true for all of my cousins. $\endgroup$ – matt mods Aug 9 '17 at 15:08
  • $\begingroup$ @mattmods - this is the problem highlighted in my answer. Nobody knows the definitive answer to how Autism develops, however the situation you describe with your family line is known to happen, again as indicated. Let's hope they find the answer soon $\endgroup$ – Chris Rogers Aug 9 '17 at 19:37
  • $\begingroup$ Yeah I mean I know it's quite a common pattern and such but let's just hope they find the cause soon or if not it gives me a reason to go into neuroscience I guess. $\endgroup$ – matt mods Aug 9 '17 at 21:25

Since the 1970s, researchers have found out and known that genes make a contribution to the pervasive developmental disorder or autism when two identical twins have shared a similar condition.

As the world progresses, scientists have found out the variety of genetic changes in the DNA that contribute to the autism spectrum. However, genetics cannot be solely accounted for the risks of developing signs for autism spectrum. There are various other factors involved as well,

  • A child being born to older parents
  • Low birth weight and premature infants
  • Hormonal and metabolic imbalances
  • Fetal exposures to the medications such as valproic acid or thalidomide
  • Exposure to heavy metals and environmental toxins
  • Fragile X syndrome and other inherited disorders
  • Having an immediate family member with autism

Working with Arizona Centers for Comprehensive Education and Life Skills, I have realized children or adults with pervasive spectrum need distinctive care and affection.


Some of the information contained in this post requires additional references. Please edit to add citations to reliable sources that support the assertions made here. Unsourced material may be disputed or deleted.

  • 1
    $\begingroup$ Welcome to psych.SE! Your answer would be much more useful with citations for the factors you mention, both so that the original questioner has a way to find more information and so that all your readers know what technical perspective you're speaking from. $\endgroup$ – Krysta Nov 27 '18 at 14:12

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