Abstract
A classical twin study was used to estimate the magnitude of genetic and environmental influences on four measurements of within-person variability: dominance flux, warmth flux, spin and pulse. Flux refers to the variability of an individual's interpersonal dominance and warmth. Spin measures changes in the tone of interpersonal styles and pulse measures changes in the intensity of interpersonal styles. Daily reports of interpersonal styles were collected from 494 same-sex female twins (142 monozygotic pairs and 105 dizygotic pairs) over 45 days. For dominance flux, warmth flux, and spin, genetic effects accounted for a larger proportion of variance (37%, 24%, and 30%, respectively) than shared environmental effects (14%, 13%, 0%, respectively), with the remaining variance due to the non-shared environment (62%, 50%, 70% respectively). Pulse appeared to be primarily influenced by the non-shared environment, although conclusions about the contribution of familial influences were difficult to draw from this study.