Effects of Inheritance and Environment on the Heights of Brothers in Nineteenth-Century Belgium.

Shared genetic inheritance results in a high correlation in the heights of brothers, but experiences in childhood and adolescence can intervene. Poor diet, disease, and heavy labor can prevent the achievement of height potentials. If families cannot control variations in these conditions, the heights of brothers will be less strongly correlated. We use heights measured at military conscription examinations from three communities in nineteenth-century Belgium. The Generalized Estimating Equation procedure allows us to estimate effects of covariates on mean heights as well as the correlations within families. Both average height and the correlation of brothers' heights differed by socioeconomic status. Members of the local elite were taller and the heights of brothers in those families were more strongly correlated. This suggests that elite families were much better able to control the environmental challenges faced by their offspring.