Control of Heredity: Eugenics 289 



would not or should not be room for it in all the libraries of the 

 world. It is generally admitted that few lines are wholly free 

 from hereditary defects and the question has often been asked 

 what the eugenical practice should be in such cases. Of course 

 people with really serious hereditary defects should not have 

 children. If the defects are slight Davenport has suggested that 

 they may either be disregarded or weakness in any character may 

 be mated with strength in that character. That people with only 

 slight hereditary defects should not marry at all is a counsel of 

 perfection. 



On the other hand it would be a dangerous rule to propose that 

 persons having really serious hereditary defects should be mated 

 with those who are strong in those characters on the ground that 

 in general strength in a character is dominant over weakness. It 

 has been suggested that a normal man who marries a feeble- 

 minded woman would have only normal children, since both 

 genius and feeble-mindedness seem to be recessive when mated 

 with mediocrity or normality. But in all such cases the weakness 

 is not neutralized or removed but merely concealed in the offspring 

 and is therefore the more dangerous. If a man chooses to marry 

 a feeble-minded woman he at least does so with his eyes open and 

 he need not be deceived. But the normal and perhaps capable 

 children of such a union carry the taint concealed in their germ 

 plasm and if they should be mated with other normal persons 

 carrying a similar taint some of their children would be feeble- 

 minded, and thus the sins of the parents in mating weakness with 

 strength would be visited upon the children to the nth genera- 

 tion. Such a policy of concealing weakness by mating it with 

 strength is wholly comparable with the custom once prevalent of 

 concealing cases of contagious diseases, and may properly be char- 

 acterized as the "ostrich policy." 



After all in the choosing of mates a combination of instinct 

 and intelligence is probably the safest guide. Our instincts, built 

 up through long ages, are generally adaptive and useful, and if 

 they be guided by reason the result is apt to be better than if 



