THE INHERITANCE OF FAMILY TRAITS 59 



11. Calculating Ability 



The inheritance of great mathematical ability cannot be 

 denied and is well illustrated in the case of Bernoulh: Jac- 

 ques, his nephews Nicholas and Jean, and three nephew's 

 sons were mathematicians of high rank. 



Our Family Records afford a limited amount of data on 

 the subject of inheritance of mathematical ability. They 

 do give information concerning the inheritableness of the 

 ability to calculate — a broader phenomenon. The follow- 

 ing rule seems justified: When both parents are good at 

 calculating all (or nearly all) of their children will be so 

 likewise. 



Of 728 offspring of this class of matings all but 48 (or 8 per cent) were 

 good at calculating. In no case were both parents returned as poor at 

 calculating; but in 47 matings both parents were only medium and 13 

 per cent of their children were poor at calculating. 



12. Memory 



There is no doubt that people vary in their ability to 

 remember and there is no question that a good memory 

 is an innate quality. Phenomenal memories are often asso- 

 ciated with mental defect in which case it is clear they are 

 independent of training. In other cases they are associated 

 with high scholarship. Thus Galton cites the case of Rich- 

 ard Porson, an eminent Greek scholar, whose memory 

 became stupendous. His mother had a remarkable memory 

 and so did his sister. 



The Family Records throw some hght on the inheritance 

 of a good memory; although the term is a relative one and 

 lacks in precision. Nevertheless for a preliminary study 

 the data are not to be despised although there are not a 

 few exceptions to any generalizations one may hazard. 



When both parents have an exceptionally good memory 



