AbstractDigital patterns of a sample of monozygotic and dizygotic twins were analyzed to obtain heritability values for the four basic types of patterns: arch, tented arch, loops, and whorls. Loops have been separated according to their orientation radial or ulnar. To carry out this study, we used the Holzinger and Clark indices. The results show highest concordances for monozygotic twins except for ulnar loops of the left hand and radial ones of the right hand. Different values of heritability were found for the right and left hands, with finger I having the highest values.