Genetic and environmental sources on familial transmission in Biscayan families. III. The dynamometric strength.

The present research analyses a cross-sectional sample of 284 individuals (86 fathers, 86 mothers, 54 sons and 58 daughters) in 86 nuclear families living in the province of Biscay (Basque Country, Spain), with the aim of estimating both transmissible and non-transmissible components acting on familial resemblance for the maximum dynamometric strength of both hands, by means of a path analysis. Standardised data of each generation and sex were adjusted to a BETA model of path analysis independent of sex effects, allowing nevertheless the possibility to differentiate between transmissible (genetic and cultural) and non-transmissible (environmental) components acting on the observed phenotypic variance in Biscayan offspring. The results supported the full model of familial transmission for the two variables, in addition to other reduced models that gave rise to transmission effects regardless of any influence from the siblings' shared environment on the environmental transmitted component from their parents (b = 0), and without social homogamy between mates (u = 0). The most parsimonious model created, based on the previous ones, was accepted for both traits. The total transmissible variance (t2) explained between 21% (right hand) and 44% (left hand) of the observed phenotypic variation. These values are close to those from the literature (t2 = 37%). However, we should take into account that these kinds of estimations are specific for each group or population.