The percentage of Schizophrenia in First degree relatives is

(C) 6.4% # Genetic factors are involved in at least a subset of individuals who develop schizophrenia. Schizophrenia is observe d in 6.6% of all first-degree relatives of an affected proband. If both parents are affected, the risk for offspring is 40%. The concordance rate for monozygotic twins is 50%, compared to 10% for dizygotic twins.