Observations on Serum Cholesterol Levels in the Twin Population of Evans County, Georgia

Abstract

Important factors affecting the variation in cholesterol were found to be the genotype of the individual, age, and type of residence. The effect of genotype is clearly shown in comparing MZ twins with their matched pairs. The difference between MZ twins and their matched pairs was large and statistically significant, while for DZ and UD twins the difference was so small it could easily have been due to chance. In interpreting the significance of the effect of type of residence, we are also comparing two age groups that are almost nonoverlapping, so that adjustment for age by covariance might be questionable, since it involves extrapolating beyond the limits of the data. Thus, it seems that two important sources of variation of cholesterol have been isolated: type of residence or age which is confounded or entangled, and genotype.