Genetic and environmental influences on the covariance of facets defining the domains of the five-factor model of personality

Multivariate genetic analyses were applied to the six facets defining each of the five personality domains (Neuroticism, Extraversion, Openness to Experience, Agreeableness, and Conscientiousness) assessed by Costa and McCraeʹs Revised NEO Personality Inventory (NEO-PI-R). The analyses are designed to partition the observed covariance of facets defining each domain into their genetic and environmental bases to determine the basis for their coherence as a domain. The analyses were applied separately to a sample of 253 identical and 207 fraternal twin pairs from Canada and 526 identical and 269 fraternal pairs from Germany. Results showed that each of the NEO-PI-R domains is composed of multiple genetic and environmental factors common to the facets supporting the observed coherence of the NEO-PI-R facet sets. Differences between the German and Canadian sample appeared limited to the magnitude of the genetic and environmental effects on each facet, but not the number or type of genetic and environmental influences.