An Italian twin study on psychological well-being in young adulthood

The twin method was applied to investigate the genetic and environmental architecture of six dimensions of psychological wellbeing (PWB), that is, autonomy, positive relations, purpose in life, selfacceptance, environmental mastery and personal growth, as assessed by the shortest 18-item version of the Ryff’s Scales of Psychological Well-Being. The study sample included 742 twins (284 complete pairs, 174 unmatched twins) aged 23–24 years from the populationbased Italian Twin Registry. Genetic factors accounted for a moderate to substantial roportion of variance in the six PWB dimensions, with heritabilities between 37 and 64%. Genetic correlations were very high (range: .77–.99), indicating that genetic factors that influence the expression of the different facets of PWB may be shared to a large extent. Unshared environmental correlations were also substantial to high, with the exception of autonomy with the dimensions of purpose in life (.22), self-acceptance (.09) and personal growth (.01). These findings may guide attempts to design intervention strategies aimed at promoting physical and mental health, which are known to be linked with PWB.