Abstract
The radial longitudinal, proximal and distal transversal creases in the handline appear in the third to seventh fetal months and once formed do not change by age (WÜTRTH, '36-'37 and OBATA, '56). 94.62% (GRÜNLERG '28), 69.5% (TAKANUJHI, '42) and 75.7% (TILLNER, '56) of the children whose parents have both shown the united type of the radial longitudinal and proximal transversal creases, the so-called geschlossenes M-Figur, in their handlines have shown the same pattern. GRÜNBERG states that 90.63% in 16 pairs of monozygotic twins and 75.14% of 14 pairs of dizygotic twins have had both of the twins show the geschlossenes M-Figur in their handlines.
The authors have based this study of the hereditary tendency of the handline on data gathered from 138 pairs of twins, 50 pairs each of male and female monozygotic twins (ZZ), 20 pairs each of male and female homosexual dizygotic twins (ZZ) and 18 pairs of heterosexual dizygotic twins (PZ) of the Tokyo University Twins Research Group.
The authors have classified these as the open-type, the meet-type, the cross -type (intersecting), the sub close-type (partially-closep) and the closetype in the radial longitudinal and the proximal trasversal creases (Fig. 2), also as types I, II, III, and IV in the distal transversal crease (Fig. 3). Since there were no significant difference between the male and female EZ pairs, and between the male and female ZZ, and PZ pairs, the authors have united these classes, calling the former, the EZ group and the latter the ZZ group.
The significant differences in the coincident rate of types in a pair between the EZ and ZZ groups in the same side have been recognized at a 1% significant level in each classification (Fig. 4, 5 and 6). Namely, an hereditary tendency has been recognized in the patterns of these creases. Moreover, from the x2 each difference and the ratio of coincident rate in EZ and in ZZ pairs, it has been ascertained that the hereditary tendency is more obvious in the pattern of radial longitudinal and proximal transversal creases than in the pattern of the distal transversal creases.
The authors have also considered the relationship of the types to each other in each pattern by the ratio of a correlative rate of one type to another in EZ and in ZZ pairs (Fig. 7).
The relationship of one type to another has been more clearly illustrated in Fig. 8. The relationship of the two types as to the pattern of the distal transversal crease is illustrated in Fig. 9. It is very interesting to compare this diagram with the family study by TAKANUSHI ('42) who has concluded that the separate and united types of two creases seem to be dominant in the same degrees over the intersecting type.
With regard to the mirror image, the authors have mentioned only the patterns of the radial longitudinal and proximal transversal creases (Figs. 10 and 11). On the coincident rate of types in a pair between the EZ and ZZ groups, a significant difference has been recognized at a 1% significant level. Comparing the ratio of the coincident rate in EZ pairs to that in ZZ pairs in the opposite side (mirror image) with the ratio in the same side, it seems that the hereditary tendency is more obvious in the same side than in the mirror image. The authors have in passing indicated that the coincident rate is higher in the same side of EZ pair (73.5% ), than in the opposite side of EZ pair (65.0%) as well as in both hands of the individual (65.7%).
