26o GENETICS 



uals had produced a large effect on temperament, emotions, 

 and social attitudes, but had had little effect on such mat- 

 ters as are tested by Intelligence tests. 



An illuminating contrast with these results is given by the 

 first pair studied by Newman. The twin sisters ("O" and 

 "A") were born In London and were separated at the age 

 of 1 8 months. One lived in Ontario, Canada, the other in 

 London. Their environments were very different. When 

 they were tested, this pair gave differences in those tests in 

 which Muller's pair gave similarities, and gave similarities 

 in those tests in which Muller's pair gave differences. New- 

 man says: "The twins dealt with in this paper are very dif- 

 ferent in mental capacity." But they showed great similar- 

 ity in their manifestations of will and temperament, and 

 in their emotional reactions. So this pair of twins shows 

 that differences in the experiences undergone affect deeply 

 the individual's mental traits: his performance in matters 

 brought out by Intelligence tests. 



Important points were brought out in the study of New- 

 man's second pair, twin sisters ("E" and "G"). The two 

 had received very different educations; one had attended 

 school seven years longer than the other. Newman sum- 

 marizes as follows the results of his study of these: 



"These twins, remarkably similar after being separated 

 at 1 8 months of age and unknown to each other for 19 

 years, have been profoundly modified by the very different 

 educational careers. In every test of mental capacity, 

 whether of so-called native ability or of achievement, 'G,' 

 the more highly educated twin, has distinctly the superior 

 mind. Obviously mental training improves the ability of an 

 individual to score well In any sort of test." But further, 

 "in contrast with the great difference in mental power 

 stands the fact that in all the tests of emotional traits and 

 of temperament the twins gave the impression of being 



