Both of Mary's Parents Have Been Diagnosed with Schizophrenia

Both of Mary's parents have been diagnosed with schizophrenia. Bob has an identical twin who has schizophrenia. Who is more likely to develop schizophrenia and why?

A) Bob because he has inherited the same susceptibility that his twin is expressing.
B) Mary because females are more susceptible than males to the genetic forms of schizophrenia.
C) Mary because all of her genes come from her parents and they both have the disease.
D) Bob because he is male and has a family history of schizophrenia.