Dozens of studies have indicated that individuals more prone to experiencing disgust have stronger symptoms of anxiety disorders—especially contamination sensitivity. However, no work has informed the degree to which this relationship arises from genetic factors versus environmental factors. In the present study, we fill this gap by measuring disgust proneness and contamination sensitivity in a sample of 7,199 twins and siblings of twins, including 1,411 complete twin pairs. Disgust proneness was related to contamination sensitivity, r = .32. Multivariate twin modeling revealed that genetic factors accounted for 34% and 40% of the variance in disgust proneness and contamination sensitivity, respectively, and that the correlation between the two traits reflected overlapping genetic (54%) and unshared environmental (46%)—but not shared environmental—influences. Although consistent with work indicating that disgust proneness relates to contamination sensitivity, results suggest that prevailing parental-modeling hypotheses for explaining this relationship be reevaluated.