Regarding Genetic Factors in Schizophrenia, Which of the Following Statements

Regarding genetic factors in schizophrenia, which of the following statements is false ?

A) When one identical twin has schizophrenia, the other twin has a 45% to 50% chance of having the disorder.
B) About 13% of people with a schizophrenic parent develop the disorder themselves.
C) The closer the genetic relationship a person shares with a schizophrenic individual, the greater the likelihood that the person will have or develop schizophrenia.
D) Investigators have identified a single gene that is responsible for creating a genetic predisposition for schizophrenia.
E) Heredity plays an important role in schizophrenia, but biological and environmental factors also play important roles.