According to an analysis identical twins with autism spectrum disorder (ASD) often experience large differences in symptom severity even though they share the same DNA. The findings suggest that identifying the causes of this variability may inform the treatment of ASD-related symptoms. The study was conducted by John Constantino M.D. of Washington University School of Medicine in St. Louis and colleagues. The study was published in the journal Behaviour Genetics. ASD is a developmental disorder that affects how a person behaves interacts with others and learns. Previous studies have found that when one identical twin has ASD chances are extremely