Diagnostic Efficiency of Fingerprint and Blood Group Differences in a Series of Twins

Abstract

SummaryData obtained in a study of mentally defective twins permitted the examination of interdependence and efficiency of blood groups and fingerprints in zygosity diagnosis. After exclusion of Down's syndrome, the series consisted of 49 MZ pairs, 52 DZ pairs and 18 pairs of uncertain type.Same-sex pairs discordant for Down's syndrome seemed to include some pairs of uniovular or irregular origin, but this could not be investigated cytologically. Concordance appeared to occur independently in different blood group systems. However, DZ twins concordant in the ABO blood groups were significantly more similar in their fingerprints than were other pairs, and the within-pair differences were more uniform.Linear discriminant functions designed for zygosity diagnosis make much better use of dermatoglyphic information than do simpler measures, and the latter could not be much improved by comparing left and right hands separately.