Hallux valgus (HV) is a common foot deformity of multifactorial etiology, but knowledge about the relative importance of genetics and environments on HV has been limited. In order to estimate genetic influences on HV, 1,265 adults, including 175 monozygotic twin (MZ) pairs, 31 dizygotic twin (DZ) pairs, and 853 first-degree singleton family members of the twins were included from the Healthy Twin study, a population-based twin-family cohort in Korea. All participants underwent foot examination and weight-bearing radiographic assessment (anterior-posterior and lateral) in addition to a general health survey. Of the subjects, 208 (16.4%) were classified as HV (as HV angle >20°). The genetic influence on HV was estimated to be substantial; the heritability of HV was 0.51 (95% CI 0.42–0.59) and the heritability of HV angle was 0.47 (0.38–0.56), while contributions from shared environmental effects were negligible. These findings suggest that genetic factors play an important role in determining HV deformity.