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Previous research has indicated that extraversion and neuroticism are substantially affected both by genotype and environment. This study assesses genetic and environmental influences on the other three components of the five-factor model of personality: Openness to Experience, Agreeableness, and Conscientiousness. An abbreviated version of the NEO Personality Inventory (NEO-PI) was administered to 82 pairs of identical twins and 171 pairs of fraternal twins reared apart and 132 pairs of identical twins and 167 pairs of fraternal twins reared together. Estimates of genetic and environmental effects for Openness and Conscientiousness were similar to those found in other studies of personality: Genetic influence was substantial and there was little evidence of shared rearing environment. Results for Agreeableness were different: Genetic influence accounted for only 12% of the variance and shared rearing environment accounted for 21% of the variance. Few significant gender or age differences for genetic and environmental parameters were found in model-fitting analyses.

In this first behavioral genetic study of personality in the last half of the life span, results are reported using the powerful adoption/twin design that compares identical and fraternal twins reared apart and identical and fraternal twins reared together. Traits studied were the EAS temperaments (emotionality, activity level, and sociability), traits that show substantial genetic influence in childhood. It was hypothesized that the EAS traits would also show significant genetic influence later in life and that most of the environmental variation would be nonshared--that is, twins reared together would show no greater resemblance for the EAS traits than twins reared apart. Both hypotheses are supported.

Two aspects of perceived control, locus of control (LOC) and perceived competence (COM), command significant attention in personality and aging research. Mainly, these concepts are regarded as stable variables of considerable promise for predicting a range of outcomes. The authors concentrate on week-to-week within-person variability in self-reported LOC and COM. Using data collected over 7 months, the authors first demonstrates that the responses of a panel of older participants are structurally consistent with dominant conceptions of perceived control and that the responses maintain an underlying structure over the frequently repeated protocol. They next show that the within-person variation over weekly measurements is coherent information rather than "noise" and that individual differences in magnitude of week-to-week variability are a relatively stable attribute that predicts mortality status 5 years later. Implications of the findings for both methodological and substantive concerns are discussed. [ABSTRACT FROM AUTHOR]