520 INHERITANCE OF MENTAL TRAITS 



ranked with popes in intelligence. (7) Wood's study of 

 heredity in the royal families of Europe shows that sons 

 who inherit thrones and fortunes are but little more 

 likely to be numbered by posterity among the great than 

 are their younger brothers. 



The Inheritance of Genius. — The genius is not 

 sharply differentiated from other human beings, but is 

 merely a person of very superior ability in one or more 

 lines. All degrees of mental ability tend to be trans- 

 mitted, and genius is no exception to the rule. Galton 

 found that 977 men of genius whom he studied (" genius " 

 being defined as that degree of ability possessed by the 

 most intellectually eminent person in a population of 

 4.000) had a total of 535 fathers, brothers, sons, grand- 

 fathers, grandsons, uncles and nephews as eminent as 

 themselves. It has been calculated that this is about 

 135 times as m^ny eminent reliatives as would be found 

 for 977 average men. Of 1030 British men and women 

 of genius studied by Ellis, 40 per cent had either a father 

 or mother of very superior ability. An extensive study 

 of several hundred gifted children of California, each of 

 whom equalled or exceeded in intelligence the brightest 

 out of 200 children taken at random, showed that these 

 also had several times as many relatives of superior 

 ability as do children of average intelligence. 



Convincing evidence has also been found for the heri- 

 tability of artistic and musical ability. In 30 families in 

 which both parents were artistic, Galton found that 64 

 per cent of the children showed special talent in art. This 

 was three times the proportion found in families in which 

 neither parent was artistic. Musical ability, especially, is 

 prone to " run in '' families. The Bach family, for ex- 

 ample, produced in eight generations no less than 57 

 individuals of very superior musical ability, 20 of whom 

 became eminent. 



Inheritance of Feeble-Mi ndedness. — Investiga- 

 tions by Goddard, Davenport and others have shown that 



