Abstract
Incorrect estimation of own absolute and relative abilities is common and can have detrimental effects on a person’s educational, social, employment, and financial outcomes. It is not yet fully understood from where interpersonal differences in overconfidence emerge. In this paper, we estimate the heritability of two types of overconfidence, overestimation, and overplacement, in a sample of 1120 twins. We find that the genetic heritability of overestimation (overplacement) is about 19% (17%) and that most of the interindividual variation in overconfidence is due to individual-specific environmental factors.