Scientists at King’s College London have collected evidence from a population-based sample revealing that genetic factors outweigh more moderate environmental influences regards risk of autism and related traits in personality. They published their results online this week in JAMA Psychiatry.

Over 6,000 twins, born in England and Wales between 1994 and 1996, with a variety of autism-related traits – high and low subclinical levels, as well as ASD, – participated in several evaluations: the Childhood Autism Spectrum Test (6,423 twins), the Development and Well-being Assessment (359), the Autism Diagnostic Observation Schedule (203), the Autism Diagnostic Interview-Revised (205), and a best-estimate diagnosis (207) – and all of them showed consistency in their results. […]

“Our main finding was that the heritability of ASD was high. These results further demonstrate the importance of genetic effects on ASD, despite the dramatic increase in prevalence of the disorder over the last 20 years,” said lead author Beata Tick in a statement.

“They also confirm that genetic factors lead to a variety of autistic skills and behaviors across the general population,” Tick added. […]

Our findings add weight to the view that ASD represents the extreme manifestation of autistic skills and behaviors seen in the general population,” Bolton added.


Prenatal inflammation linked to autism risk, January 24, 2013 News Release – National Institutes of Health NIH.


The average Icelandic father today at the time of conception is about 33 years old; much older than in the past. The authors explained that epidemiological studies carried out in Iceland have demonstrated that schizophrenia or autism risk in offspring is considerable greater the older the father is.


Rise In Autism Rates Partly Due To Older Fathers.

Since men are waiting to have children until much later in life, this may explain the rise in autism cases. Rob’s father was 31 when Rob was conceived; my father was the same age when he conceived my brother (AS and bipolar).

Vitals – Obese moms may be more likely to have autistic child, study suggests.

Researchers found that the risk of autism increased by nearly 70 percent when moms were obese during their pregnancies, while the risk of a having a baby with some other neurodevelopmental disorder doubled, according to the study published early online Monday in Pediatrics . . . He noted that U.S. autism rates have increased along with obesity rates and said the research suggests that may be more than a coincidence.


I gained more weight with Rob than I did for my firstborn daughter, Joy. It was especially pronounced at the end of the pregnancy, when I suddenly put on ten pounds in a week. They did a gestational diabetes test, which showed that I was borderline. Rob was 10 lbs 10.5 oz at birth, but did not lose any of that weight afterward.

If this is a factor, then why is autism also associated with low-birthweight babies?