Variability in Anthropometric Traits in Twins and Their Families

Abstract

Studies of twins and their families can provide important insight into the nature of the factors responsible for observed phenotypic variation in anthropometric traits as well as for differences in risk for multifactorial disorders. Classical twin studies afford an incisive means for determining whether or not genetic factors contribute to observed differences in the occurrence of a trait or disorder. The kinships of twins are particularly valuable for differentiating between genetic, environmental and maternal effects and the causes of sex differences in gene expression because of the unusually large number of informative genetic and environmental relationships that are contained within each extended pedigree. This approach is especially productive when dealing with traits, such as blood pressure, which could be influenced by a number of different factors. While there has been general agreement that genetic differences are responsible for at least some of the observed variation in normal blood pressure, there is less consensus as to the relative magnitude of this effect. Thus in different studies genetic factors have been both implicated in (Moll et al., 1983; Morton et al., 1980; Annest et al., 1979; Ewell et al., 1978), and absolved of (Iselius et al., 1983; Harburg et al., 1977; Chakraborty et al., 1977) being the primary causal determinant of variation in blood pressure.