[Craniofacial dimensions in twins]

In order to estimate the role of the genetic and ecological factors in the craniofacial growth, study has been made on 36 monozygotic (MZ) and 31 dizygotic (DZ) twin pairs of the same sex. Standard anthropological instruments were used. The following dimensions were examined: the stature, Eu-Eu, G-Op, Zy-Zy, Go-Go, N-Gn and N-Pr. The results are represented in 2 tables and 3 histograms. The result indicate the largest variability of N-Pr and the smallest variability of Zy-Zy within the MZ twins while within the DZ twin pairs it is revers, which suggests that the bizygomatic width is more genetically dependent than the upper height of the face. No statistically significant differences occur within the MZ pairs, except for the stature. On the other hand, within DZ pairs the differences are statistically significant (except for G-Op). The intracorrelations are greater for all the MZ variables. The heredity and cultural inheritance index show higher value of c2 for all variables, which suggests a higher influence of the environmental than that of the genetic factors (h2). A hypothesis would be that the shape of the head and the upper facial height are easily influenced than the Zy-Zy and the morphological face height.