Case Workbook for Human Genetics 9th Edition by Ricki Lewis

Exercise 4

In autistic disorder, a child ceases communicating and develops abnormal repetitive behaviors. Siblings have a 3 to 5% risk of also being affected. Twin studies indicate concordance of 69-98%, which is considered to be very high. How can sibling studies suggest a minimal genetic component, yet twin studies suggest the opposite? What experimental approach might reveal more about causes of autistic disorder?