146 HEREDITY AND EUGENICS 



between brothers and sisters (siblings) comes out 

 0-51 for physical and 0-52 for mental characters. 

 Schuster and Elderton (1907), from a statistical 

 survey of Oxford class lists, attempted to determine 

 the correlation in mental ability between father and 

 son, and between brothers who attended the Uni- 

 versity. The}^ found r=o-3i2 for father and son, 

 and ^=0-405 for brothers. They agree with Pearson 

 that mental and physical characters are inherited 

 with the same intensity. 



. Pearson has recently (191 9) considered the subject 

 again from different data, comparing the results of 

 applying the Binet-Simon test (a) to children in 

 orphanages in California, hence under nearty uniform 

 conditions ; (b) to children in schools of Great 

 Britain, under the greatest variety of conditions of 

 education and home training. Although the mental 

 environment w^as relatively uniform in one set of 

 data and diversified in the other, yet the correlation 

 of intelligence betw^een siblings w^as the same in both 

 groups, the resemblance, r =0-508 in the Californian 

 and r=0'5i5 in the English data, indicating that 

 heredit}' and not environment determined the differ- 

 ences in all cases. 



But the situation as regards some ps3^chical charac- 

 teristics is beyond our present powders of accurate 

 anal3^sis. This is probably because we have not yet 

 learned to define ps^^chic characters in biological 

 terms. That psychologists are beginning to recognise 

 the necessity for an analysis of the mind from the 

 point of view of the inheritance of mental traits, is 

 shown particularly b}^ McDougall's book. Psychology, 

 the Study of Behaviour {e.g., p. 187). In writing of 

 the very close resemblances in intellect and character 

 which twins often show, he says : " The more children 

 are studied from this point of view, the more far- 

 reaching does the influence of heredity appear." At 



