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August 24, 1929


JAMA. 1929;93(8):612-613. doi:10.1001/jama.1929.02710080038016

The existence of twins offers unusual opportunity for physical and psychologic studies of mankind with relationship to the influences of heredity and environment. In 1925, Muller1 made a study of a pair of identical twins who had been reared apart. Now Prof. H. H. Newman2 of the University of Chicago has made detailed and extended studies of a series of identical twins reared under different environments, and he derives from his studies several conclusions of great interest for the investigation of human reactions in general. In one instance identical twins were separated at the age of 18 months; one was reared in Canada and the other in England, and they were separated for seventeen years. Careful studies of these two girls, using all the well known methods of physical examination and psychologic testing, led to the conclusion that differences in environment and in training were responsible for bringing