That both of nonidentical twins should show the characteristics of mongolism is a sufficiently rare occurrence to merit interest. It has been stated that no two ovum pregnancy has been reported in which both children showed mongolism,1 and Rosanoff and Handy2 in 1934 in a review of all published cases of mongolism in twins did not record any instance in which dizygotic twins were both affected. However, I found one such case reported in an English journal,3 and I record one here.
Less than twenty records can be found mentioning mongolism in more than one member of a family.4 There is one report of four sisters with the condition.5 The occurrence of more than one case of mongolism in a family has certainly been noted, but it is rare. From the eugenic point of view, Popenoe6 stated that the mother of a child with