TWIN AFFINITIES

Dominion, Volume 24, Issue 143, 13 March 1931, Page 8

TWIN AFFINITIES

Research Work in London # , ■» I The examination of more than SOO twins in London County Council schools, over a period of two years, has epabled 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 mav 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 resemblance 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 resemblance alone, and that fraternal twins would differ, as photoThe finger-prints, however, form the conditions at the same age, show slight differences. This, however, is far from true. . Dr. Stocks says he finds that in-hke-sexed twins only two-thirds can be labelled "identical” or “fraternal” on the score of facial resemblance. e . graphs of two brothers, taken in similar most valuable tests, together with anthropometric measurements. . Dr. Stocks incorporates his observations into a table which suggests that "identi-. cal” twins possess anthropometric resemblances with each other amounting to between 80 and 90 per cent.—-absolute resemblance being taken as 10O—and ternal” twins vary between 39. and oo per cent., while the brothers or sisters oi cither type of twin resemble each, other to the extent of from 32 to 49 per cent.