Incidence of three Mendelian traits, viz ABO blood, Rh blood group and
PTC taste ability was studied in randomly selected representative sam
ples of five endogamous populations of Purnia, Bihar. Allelic frequenc
y was calculated and the biological distance between the pairs of popu
lations estimated by Nei's formula. On the basis of genetic distance (
D) two main clusters were found-one for Muslims and the other for non-
Muslims (Rajput, Brahmin, Bania and Kayastha).