HEREDITY 



ances for differences in opportunity; and eminence is 

 certainly not a precise measure of intelligence. Yet, in 

 spite of their deficiencies, these analyses have yielded some 

 very significant results. Each investigator finds that the 

 relatives of great men have a very much greater chance of 

 becoming eminent than people selected at random from the 

 general population. The difi*erence is too great to be 

 accounted for by any assumed difference in opportunity. 

 Moreover, it is to be noted that the chance of becoming great 

 varies directly with the closeness of genetic relationship. One 

 must agree with Cattell, of course, that environment holds 

 a veto over mental development, but one cannot avoid the 

 conclusion that environment merely harnesses the forces of 

 heredity. 



Such investigations go far toward establishing Galton's 

 important generalization that no man is likely to attain 

 eminence unless he possess innate ability of a high order. 

 They also support his further conclusion, though perhaps 

 they do not establish it, that "few who possess these very 

 high abilities can fail in achieving eminence." In other 

 words, it is hard to keep a good man down. Or woman 

 either. An instance is Helen Keller. Cattell once said that 

 if Isaac Newton had been born among Hottentots, he would 

 have announced no Laws of Motion. True enough. But 

 he would have been the intellectual leader of the tribe. A 

 few Hottentot Isaac Newtons, and the group would have 

 had a different cultural history. 



The evidence from identical twins points in the same 

 direction. Identical twins come from a single fertilized egg. 

 Each member of the pair, therefore, has the same heredity. 

 And such twins exhibit mental attributes as well as physical 

 characteristics which are much more nearly alike than are 

 the traits exhibited by other children of the same family. 

 They even tend to show this same similarity when they are 

 separated at an earlv age and reared under different con- 



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