Quiz 8: Genetics of Behavior

Depression is a multifactorial trait. List three types of evidence that would suggest a large hereditary component to the illness.

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?

The incidence of schizophrenia in the general population is 1%. Offspring of two people with schizophrenia have a risk of 13%. Why isn't this risk 25%, as Mendel's first law predicts?

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?

If your identical twin had these conditions, what is the chance that you would too? a. schizophrenia b. narcolepsy with cataplexy c. Alzheimer disease