Healthy personality, that of a fully functioning person: Around 30pct is additive genetic; the rest is non-shared environmental effects; shared environment has almost null effect

Bleidorn, W., Hopwood, C. J., Ackerman, R. A., Witt, E. A., Kandler, C., Riemann, R., . . . Donnellan, M. B. (2019). The healthy personality from a basic trait perspective. Journal of Personality and Social Psychology, http://dx.doi.org/10.1037/pspp0000231

Abstract: What basic personality traits characterize the psychologically healthy individual? The purpose of this article was to address this question by generating an expert-consensus model of the healthy person in the context of the 30 facets (and 5 domains) of the Revised NEO Personality Inventory (Costa & McCrae, 1992) system of traits. In a first set of studies, we found that the healthy personality can be described, with a high level of agreement, in terms of the 30 facets of the NEO-PI-R. High levels of openness to feelings, positive emotions, and straightforwardness, together with low levels on facets of neuroticism, were particularly indicative of healthy personality functioning. The expert-generated healthy personality profile was negatively correlated with profiles of pathological personality functioning and positively correlated with normative personality functioning. In a second set of studies, we matched the NEO-PI-R profiles of over 3,000 individuals from 7 different samples with the expert-generated healthy prototype to yield a healthy personality index. This index was characterized by good retest reliability and cross-rater agreement, high rank-order stability, and substantial heritability. Individuals with high scores on the healthy personality index were psychologically well-adjusted, had high self-esteem, good self-regulatory skills, an optimistic outlook on the world, and a clear and stable self-view. These individuals were low in aggression and meanness, unlikely to exploit others, and were relatively immune to stress and self-sufficient. We discuss the results in the light of their implications for both research and theory on healthy personality functioning.