Path analysis of family resemblance for cranio-facial traits in Andhra Pradesh nuclear families and twins.

Path analysis of 12 cranio-facial measurements from a sample of nuclear families and twins from Andhra Pradesh, India is used to test hypotheses about the familial transmission of these traits. For bigonial breadth and ear dimensions, the transmission from parent to child is consistent with simple autosomal polygenic inheritance, but length, breadth and circumference of the head, facial breadth and nose dimensions show evidence of transmission in excess of polygenic expectations. Additional non-transmissible resemblance of sibling pairs is not significant for any of the variables, but twin pairs do exhibit significant additional resemblance for head circumference, head length, minimum frontal breadth, bizygomatic breadth and ear dimensions. The effect of interobserver measurement differences can be detected for head breadth, minimum frontal breadth, bigonial breadth, total facial height and nose dimensions.