Health locus of control in late life: A study of genetic and environmentalinfluences in twins aged 80 years and older

The factor structure of health locus of control (Form A; K. A. Wallston, B. S. Wallston, & R DeVellis, 1978) was examined in 420 octogenarians (M age = 83.2 years), and the contributions of genetic and environmental factors t o health-control beliefs in 141 octogenarian twin pairs (71 identical, 70 s ame-sex fraternal) were estimated. Factor analyses reproduced previously pr oposed factors (Internal, Chance, and Powerful Others). Associations betwee n health-control beliefs and life satisfaction, depression, and other healt h-related measures (e.g., self-rated health, outpatient contacts, and hospi talization), were modest. Quantitative genetic analyses revealed significan t shared environmental influence on the Chance subscale, and significant fa miliality (attributable to a combination of genetic and shared environmenta l influences) on the Powerful Others subscale; there was no evidence of fam iliality on the Internal subscale.