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Summary Data are presented on the twinning rate among Europeans and Negroes. The monozygotic twinning rate is constant; there is, however, considerable variation in the dizygotic rate. The dizygotic rate is higher among Negroes than Europeans. There are also variations within these groups. In particular there seems to be a centre of low twinning rate in south‐west Europe. I should like to thank the following who have gone to great trouble in sending me data: E. A. Barker, Nqutu, Zululand; C. J. Dricot, Leopoldville; S. H. O. Jones, Bathurst, Gambia; Yayoichi Karube, Tokyo; Prof. Lambillon, Leopoldville; J. B. Lawson, Ibadan, Nigeria; J. M. Samson, Johannesburg; Prof. J. B. Stewart, Jamaica; K. H. Uttley, Antigua.
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M. G. Bulmer (1959) studied this question.
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