304 GENETICS 



mental and moral characteristics have a large share 

 in making man what he is. The brute acts according 

 to his inherited organization ; man is urged by his but 

 may act according to a higher, moral law. There is, 

 however, no fundamental scientific distinction which 

 can be drawn between moral, mental, and physical 

 traits, and they are undoubtedly all equally subject to 

 the laws of heredity. 



For instance, as an illustration of the heritability 

 of non-physical traits, in the Jukes pedigree three of 

 the daughters of Max impressed their peculiar moral 

 and mental characteristics in a distinctive way upon 

 their offspring. To quote Davenport: "Thus in the 

 same environment, the descendants of the illegitimate 

 son of Ada are prevailingly criminal; the progeny of 

 Belle are sexually immoral; and the offspring of Effie 

 are paupers. The difference in the germplasm deter- 

 mines the difference in the prevailing trait." As 

 Woods observes : "The most interesting and even 

 startling thing has been the ease with which heredity 

 has been able to bear the brunt of explaining the gen- 

 eral make-up of character." 



5. THE CHARACTER OF HUMAN TRAITS 



Of the mental, moral, and physical traits which are 

 heritable in man, some must be regarded as generally 

 desirable, some as indifferent, and others as defects to 

 be avoided if possible. In general the majority of 

 human traits, those which together make up man as 

 distinguished from other animals, do not particularly 



