Transmission of human craniofacial dimensions.

The transmissibilities of 11 human craniofacial dimensions are estimated by path analysis based upon familial correlations obtained in four different populations. Estimates from both the individual populations and from pooled correlations indicate that the observed variation in craniofacial dimensions is determined by genetic and nongenetic factors in roughly equal measure (.45 less than t 2 less than .60). These results implicate the possibility of complex gene-environment and gene-gene interactions in the development of the size and shape of the head and face and call for more detailed familial studies of these traits. This additional complexity further suggests the need for caution in interpreting such metrical variation, especially from a diagnostic or classificatory viewpoint.