title: Neuroticism, extraversion, and related traits in adult twins reared apart and reared together.
abstract: The relative importance of genetic and environmental factors for neuroticism, extraversion, impulsivity, and monotony avoidance were estimated in a sample of 99 monozygotic and 229 dizygotic pairs of twins reared apart (TRA) and a matched sample of 160 monozygotic and 212 dizygotic pairs of twins reared together (TRT). The average age was 58.6 (SD = 13.6); 72% of the twins were 50 or older. Model-fitting analyses verified the importance of genetic factors for all four measures; from 23% to 45% of the total variation was attributable to genetic sources. There was considerable evidence that these factors were operating in a nonadditive manner for extraversion and impulsivity. Shared environment accounted for less than 10% of the variance; some evidence for selective placement was found for neuroticism.
authors.affiliation: Department of Environmental Hygiene, Karolinska Institute, Stockholm, Sweden.
authors.forename: N L
authors.initials: NL
authors.lastname: Pedersen
authors.forename: R
authors.initials: R
authors.lastname: Plomin
authors.forename: G E
authors.initials: GE
authors.lastname: McClearn
authors.forename: L
authors.initials: L
authors.lastname: Friberg
mesh_terms: D004200:Diseases in Twins; D004777:Environment; D005106:Exploratory Behavior / Q000502:physiology; D005120:Extraversion, Psychological; D005260:Female; D006801:Humans; D007175:Impulsive Behavior / Q000235:genetics; D008297:Male; D008875:Middle Aged; D008957:Models, Genetic; D015233:Models, Statistical; D009497:Neurotic Disorders / Q000235:genetics*; D010551:Personality; D014427:Twins / Q000523:psychology*; D014429:Twins, Dizygotic / Q000523:psychology; D014430:Twins, Monozygotic / Q000523:psychology