Reanalysis of data on periodontal disease in 241 families [Chung et al, 1977b], based on an extended and more satisfactory path model [Rao et al, 1979], failed to detect significant heritability, and concluded in favor of cultural inheritance only, without maternal effects or intergenerational differences. The most parsimonious hypothesis yields a relative variance component of 0.338 +/- 0.024 due to indexed environment for both children and adults, the remainder (1.0--0.338 = 0.662) being due to residual nongenetic factors.