Abstract
The distinction between genetic influences on the covariance (or bivariate heritability) and genetic correlations in bivariate twin models is often not well-understood or only one is reported while the results show distinctive information about the relation between traits. We applied bivariate twin models in a large sample of adolescent twins, to disentangle the association between well-being (WB) and four complex traits (optimism, anxious-depressed symptoms (AD), aggressive behaviour (AGG), and educational achievement (EA)). Optimism and AD showed respectively a strong positive and negative phenotypic correlation with WB, the negative correlation of WB and AGG is lower and the correlation with EA is nearly zero. All four traits showed a large genetic contribution to the covariance with well-being. The genetic correlations of well-being with optimism and AD are strong and smaller for AGG and EA. We used the results of the models to explain what information is retrieved based on the bivariate heritability versus the genetic correlations and the (clinical) implications.
Highlights
The main goal of behavior genetics research is to understand the causes of individual differences in human traits and behavior
The four traits included are optimism, symptoms of anxiety or depression, aggressive behavior, and educational achievement. We chose these traits based on previous work, since we expect different associations of the traits with well-being
The four bivariate twin models fitted to data of adolescent females and males using well-being (WB; satisfaction with life) and four other complex traits, namely optimism, anxious-depressed symptoms, aggressive behavior, and educational achievement resulted in variability in the phenotypic correlations, bivariate heritability, and genetic and environmental correlations
Summary
The main goal of behavior genetics research is to understand the causes of individual differences in human traits and behavior. The opposite can be observed, that is while there is only a small influence of genetic factors on the covariance, the genetic correlation is substantial This indicates that the sets of genes that influence each trait are shared to a large extent, but that genes are not that important in understanding the association between two traits. The four traits included are optimism, symptoms of anxiety or depression, aggressive behavior, and educational achievement We chose these traits based on previous work (summarized below), since we expect different associations of the traits with well-being (i.e. different phenotypic correlations, bivariate heritability estimates and genetic and environmental correlations). The small phenotypic correlation suggests low genetic and environmental correlations with well-being
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