CHAPTER XXXIl 



HEREDITY OF GENERAL MENTAL ABILITY, INSANITY, 

 EPILEPSY, AND FEEBLE-MINDEDNESS 



One of the first investigations carried on in the la])oralory 

 of Pearson related to the inheritance of abiUty as indicated 

 by the " class lists " (rank lists) of Oxford. The investigation 

 of the relative rank of two thousand five hundred pairs of 

 fathers and sons showed that a distinct correlation exists 

 between them. If the father took high rank the son also 

 ranked high, and vice versa, in a considerable percentage of 

 cases. Expressed numerically the correlation in the Oxford 

 lists was found to be .31 where 1.00 would express exact 

 agreement in rank and would express only chance agree- 

 ment. Between four thousand two hundred brothers the 

 agreement was closer still, viz., .40. Closer resemblance was 

 indeed to be expected, since in this case the mothers as well 

 as the male ancestors were the same. The conclusion reached 

 is that mental capacity, as indicated by rank attained at the 

 University, is inherited; that the proverb "like father, like 

 son " applies in the long run to scholarship, as well as to 

 physique. This is a conclusion which every experienced 

 teacher would have anticipated. It is interesting to find that 

 it has full statistical warrant. 



But the further question arises whether success in study 

 has any relation to success in life outside of schools. Of this 

 question an investigation was made in Pearson's laboratory. 

 Rank in the Oxford B. A. examinations was compared with 

 subsequent rank in the professions, the Church and the Law. 

 The measure of success in the Church was taken to be the 

 holding of a high office in the Church or of a first-class 

 scholastic appointment. It was found that the higher the 

 classification of a man at the Oxford examinations, the 



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