Establishment of a measurement system for similarity and dissimilarity of twins

Using previous twins study methods, it is thought that assessments of a given level may certainly be derived by analysis of similarity. However, there is the drawback that analysis cannot be done without a large population of twin pairs. In this study, author attempted the combined use of WIM and cross correlation function as a method that can evaluate similarity even in small populations of twin pairs. An evaluation chart was constructed for similarity from cross correlation function statistics with random pairs in the height growth of general boys, and from that chart a cross correlation function, r of 0.9 or higher, became a standard indicating high similarity. When cross correlation functions for height growth in monozygotic and dizygotic twins are applied to this evaluation chart, the correlation in monozygotic twins is high and that in dizygotic twins is somewhat high. Higher similarity is thus seen in monozygotic twins.