Phong and Phan Are Identical Twins Who Have Been Raised

Phong and Phan are identical twins who have been raised apart in separate adoptive homes.However,both brothers have developed the same psychological disorder.What does this evidence suggest

A)  Genetic factors have more influence than environmental factors in this disorder. 
B)  Environmental factors have more influence than genetic factors in this disorder. 
C)  Neither genetic nor environmental factors contribute to this disorder. 
D)  Both genetic and environmental factors contribute equally to this disorder.