Analysis of sibling resemblance in anthropometric somatotype components

We analysed the Heath-Carter somatotype familial resemblance degree in a sample of 1350 siblings (685 males and 665 females) from 634 nuclear families in the province of Biscay (Basque Country, Spain). Sibling correlations were estimated according to maximum likelihood procedures for endomorphy, mesomorphy, ectomorphy and somatotypical attitudinal distance (SADi), after having adjusted for age, sex and the two other components (Model I), and after taking into account several environmental variables shared by all members of each sibship (Model II). All sibling correlations of the somatotype components were significant, tending to be higher in the case of mesomorphy than in the case of endomorphy. Same-sex siblings (BB and SS) displayed significant mesomorphic and ectomorphic resemblances, but in the case of endomorphy, sisters (SS) revealed relatively low correlation compared with brothers (BB). The sex of sibs had a significant influence on correlations of mesomorphy, but not on the other two components. Further control of socio-familial variables such as the father's occupation and education, and the sibship size, resulted in lower mesomorphy correlation coefficients, but had no effect whatsoever on the other two components. SADi correlations were very low and not significant, indicating high degrees of dispersion in the individual somatotypes of the sample.