Sex Differences in the Inheritance of Some Anthropometric Characters in Twins

Abstract

Biometrical genetical techniques have been applied to the analysis of certain anthropometric characters measured in 134 pairs of adult twins. After allowing for assortative mating it appears that there is a family environment (E2 ) component for variation in height larger than previously reported. "Fatness" traits -weight, ponderal index, and skinfold thickness -all show higher heritabilities in males and substantial Ez components in females, and reasons for this are discussed. The same is true for cephalic index and forearm length but the reason for these differences is not so obvious. Head length shows a much higher heritability than head breadth. A larger sample of DZ opposite-sex pairs would allow more powerful discrimination, but the variety of patterns of variation revealed by the modelfitting approach used here justify its use over more traditional techniques.

Causes of Variation in Drinking Habits in a Large Twin Sample

“…The results of this analysis (Table 2) showed that DZ regressions were no greater than their MZ counterparts. Because this test has proved powerful in detecting genetical non-additivity for other traits in much smaller samples [4,18], we conclude that directional non-additivity is not an important source of variation in alcohol consumption. A sensible hierarchy of models is to first fit E!…”

“…Alternative models of trait variation are fitted to between-and within-pairs mean squares by iterative weighted least squares [4,8,9]. A chi-square test of goodness of fit, based on expected mean squares calculated from the least-squares parameter estimates, provides a test of the adequacy of each model.…”

A twin study of ethanol metabolism

“…This was so irrespective of sex and absorption versus elimination. Age per se is not an inherited trait and weight, adiposity, and lung function are incompletely inherited (Clark et al, 1980;Gibson et al, 1983), so the contribution of these four variables to the heritable portion of total BAC variance must also have been small.…”

Genetic and environmental causes of variation in renal tubular handling of sodium and potassium: A twin study

“…A full model incorporating different sized El, VA and E2 effects for males and females [Clark et al, 1980;Eaves et al, 19781 was therefore tried. If the genes affecting a trait in males are quite different from those affecting the trait in females, then VAmf (the covariance between the genetic effects in males and females) will be zero.…”