Attention deficit hyperactivity disorder (ADHD) in children has been attributed to poor parenting skills, food additives, and too much television. A recent study showed a heritability of 0.8. What does this mean?
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?