Objective: To study the parent-offspring similarity of class II division 1 malocclusion.
Methods: On the basis of family units, the polygonic curves and superimposed graphs of parents with those of the offspring were compared.
Results: (1) Craniofacial structure of most parents of the class II division 1 patients have class II convex tendency. (2) The curves of the offspring resemble one or two of the parent's in 84% of the families, and the resemblance mainly concentrates in skeleton.
Conclusions: (1) Class II division 1 malocclusion is characterized by familial aggregativity. (2) High probability of heredity exists in parent-offspring similarity, and we believe that hereditary factors dominate in skeletal area while in dental area there is a higher probability that environmental factors dominate.