TESTS OF 800 TWINS

Wanganui Chronicle, Volume 73, Issue 460, 29 December 1930, Page 8

TESTS OF 800 TWINS

DOCTOR’S RESEARCH WORK. WHY SOME ARK MORE ALIKE. The examination of more than 800 twins in London County Council schools, over a period of two years, has enabled Dr Percy Stocks to throw further light on the resemblances and differences between twins, which he sets out in a recent number of Nature. Twins may be either “identical” or “fraternal.” In the first case they resemble each other very closely, and are of the same sex; in the second, the re semblance is less striking, and the twins are often of opposite .sexes. The existence of these two types is accounted for by the fact that “identical” twins both arise from the same maternal cell, whereas with “fraternal” twins two mother-cells give origin to them. The “fraternal” twins are thus characteristically different children of the same age instead of being identical children of the same age. One would expect that in twins of the same sex it would be easy to distinguish between the “identical” and “fraternal” type by facial resomblancv. alone, and that fraternal twins would differ, as photographs of two brothers, taken in similar conditions at the same age, show slight differences. This, however, is far from true. Dr Stocks says he finds that in likesexed twins only two-thirds can be labelled “idcntifical” or “fraternal” on the score of facial resemblance. The finger prints, however, form the most valuable tests, together with an--11 ropometrie measurements. Dr. Stocks incorporates his observations into a tnl'h 1 which suggests that “identical” twins possess anthropo matiic resem.on’i.'OF with each other amounting to betwren 80 and 90 per cent. —absolute resemblance beiig taker as 100—and “fraternal” twins ca r y between 39 and 56 per cent., whil-j the brothers or sifters of either type •*f *win resemble each other to the extent of from 27 to 49 per unt.