Inheritance of Physical and Mental Traits 



285 



of genius that often show the combination of ability and 

 insanity (Fig. 96). May it not be that just that lack of 

 control that permits "flights of the imagination" is related 

 to the flightiness characteristic of those with mental weak- 

 ness or defect ? 



These studies of inheritance of mental defect inevitably 

 raise the question how to eliminate the mentally defective. 

 This is a matter of great importance because, on the one 

 hand, it is now coming to be recognized that mental defect 



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Fig. 96. — Pedigree of a family with great inventive and artistic abilitj-, in 

 whose earlier generations appear insanity (I), suicidal tendency, and eccentricity. 



is at the bottom of most of our social problems. Extreme 

 alcoholism is usually a consequence of a mental make-up 

 in which self-control of the appetite for liquor is lacking. 

 Pauperism is a consequence of mental defects that make 

 the pauper incapable of holding his own in the world's 

 competition. Sex immorality in either sex is commonly 

 due to a certain inabihty to appreciate consequences, to 

 visualize the inevitableness of cause and effect, combined 

 sometimes with a sex-hyperaesthesia and lack of self-control. 



