Psychological well-being (PWB): A natural life outlook? An Italian twin study on heritability of PWB in young adults

Background To date, the genetic and environmental architecture of the dimensions of psychological well-being (PWB) remains unexplored.Method PWB of 742 twins aged 23-24 years and enrolled in the Italian Twin Registry was assessed with the three-item version of Ryff's Scales of Psychological Well-Being (SPWB). These scales include items for evaluating the PWB dimensions of self-acceptance, positive relations with others, autonomy, environmental mastery, purpose in life, and personal growth. A twin design was used to obtain correlations in the PWB dimensions for monozygotic (MZ) and dizygotic (DZ) twins and to estimate the contribution of genetic and environmental factors to variation and covariation in the dimensions.Results Genetic factors explained moderate to substantial proportions of variance in the six SPWB dimensions, with heritability estimates between 37% and 64%. The estimates of genetic correlations were very high (range 0.77-0.99), indicating that genetic factors that influence the expression of the different dimensions of PWB may be shared to a large extent. Non-shared environmental correlations ranged from substantial to high, with the exception of the correlation between autonomy and the dimensions of purpose in life, self-acceptance and personal growth.Conclusions This study presents a twin analysis of PWB measured by the SPWB dimensions; it was found that both genes and non-shared environment play a role in individual differences. The genetic and non-shared environmental correlations between SPWB dimensions suggest that common underlying genetic and non-shared environmental factors influence the expression of the different facets of PWB. © 2011 Cambridge University Press.