Happiness and health: environmental and genetic contributions to the relationship between subjective well-being, perceived health, and somatic illness.

The aim was to identify genetic and environmental influences on the covariances between subjective well-being (SWB), perceived health, and somatic illness. Analyses were based on 6,576 Norwegian twins aged 18-31. Heritabilities ranged from .24 to .66. SWB correlated .50 with perceived health, -.25 with musculoskeletal pain, and -.07 with allergy. Common genetic factors accounted for 45%-60% of associations. SWB and perceived health was to a high extent influenced by the same genes (r(g) = .72 and .82 for males and females, respectively). For SWB and musculoskeletal pain, r(g) = -.29 and -.42 for males and females, respectively. Effects were partly sex specific. Environmental factors shared by twins did not affect the covariances. Results support a differentiated view of SWB-health relations, and imply that both genes and environment play important roles in the associations between well-being and health.