Autistic by birth? A new study doesn't think so, after 192 pairs of single or double autistic twins were analysed for a genetic link - The study, by the Archives of General Psychiatry couldn't find a link in 62 percent of cases. "Their data are so similar to everybody else’s, and yet they come up with another conclusion, I don't know how this happened" Robert Plomin, a behavioral geneticist at King’s College London, said.

The disorder - characterised by abnormal sometimes aggressive behaviour - was traditionally believed to be 'due to lack of maternal warmth' during pregnancy.

"We now have strong evidence that, on top of genetic heritability, a shared prenatal environment may have a greater than previously realized role in the development of autism." said Clara Lajonchere, Ph.D., a co-author of the study conducted by Autism Speaks (

Identical twins which share 100 pct of genetic material are perfect for genetic studies however could not predict a tendency towards Autism when compared with near-identical (fraternal twins) who share just 50 pct of genes - outlining a range of alternative 'outside' conditions like maternal antidepressants that may cause disease in children which shared similar growth conditions but were differentiated by genes.

AGRE, Autism Genetic Resource Exchange, which Dr. Lajonchere heads, was instrumental in this study. AGRE clinical staff recruited twins to participate and performed the home-based testing of many of the study participants, using scientifically validated research measures for diagnosing autism spectrum disorders (ASD).

ASD which affects 6 per thousand, is thought to be made of three illnesses such as Asperger's and Pervasive Developmental Disorder-Not Otherwise Specified (PDD-NOS).

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