Genetic vs. environmental determinants of traits, motives, self-referential cognitions and volitional control in old age: First results from the Munich Twin Study (GOLD)

Usually, the central focus of behavior genetical twin studies has been intelligence and personality traits, such as extraversion and neuroticism. Personality characteristics in a broader sense were hardly not studied. These variables, however, are in the focus of the Munich Twin Study "GOLD" (Genetic Oriented Life Span Study on Differential Development), started by Kurt Gottschaldt in 1937 and continued and expanded in Munich since 1992. In addition to personality traits (1) motives, (2) social cognitions, such as self concept of one's own competence, internal and external control beliefs, (3) persistence and flexibility in coping behavior, and (4) volitional control of action were examined. Three topics of research are addressed: (1) A systematic longitudinal analysis from middle childhood to late adulthood, (2) a cross-sectional analysis of age differences in adults between the ages of 65 and 85, and (3) the estimation of genetic and environmental determination relying on the comparison of mono- and dizygotic twins. The present report examines two kinds of influence on individual differences in motives and social cognitions: age, and genetic/environmental determination. One can argue that age impacts motives and social cognitions in a specific way: Very old subjects should have lower scores in achievement and power motives, they should complain of loss of control, and should doubt their own abilities. On side of genetic vs. environmental determination we hypothesized that - in contrast to more genetically determined basic personality traits - personality dispositions such as motives and social cognitions are more strongly determined by environmental variables. The results of 135 pairs of twins are presented (the data collection is still in progress). A decrease in extraversion and conscientiousness, in the achievement motive as well as in the persistence of goal attainment can be shown. This, however, comes not true for the self-concept of one's own competence. The only increase can be found in external fatalistic control-related beliefs. Most of the age effects are gender-specific. Individual differences in the achievement and power motives are less determined by genes than differences in the basic personality traits extraversion and neuroticism. For the affiliation motive, however, genetic determinants play quite a prominent role. The same holds true for differences in competence- and control-related beliefs, and in flexibility and persistence which are genetically determined to a higher degree than differences in the fundamental traits.