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The National Geographic Magazine 



with plans that appeal to reason and 

 sound judgment. The mere dissemina- 

 tion of information concerning those con- 

 ditions that result in superior or inferior 

 offspring would of itself tend to promote 

 the production of the superior and to 

 lessen the production of the inferior ele- 

 ments. 



Knowledge is what is wanted, and the 

 dissemination of that knowledge among 

 the people. There is a wide field here 

 for your Committee on Eugenics, or for 

 some great national organization or so- 

 ciety devoted to the increase and dif- 

 fusion of knowledge concerning eugenics. 



CONSANGUINEOUS MARRIAGES. 



If it should be clearly shown that 

 certain classes of marriages are hurtful 

 to the offspring and others beneficial, 

 the mere dissemination of that knowledge 

 would of itself tend to promote desirable 

 and prevent undesirable unions of the 

 sexes. Would any reasonable person, for 

 instance, think of marrying his first 

 cousin, any more than he would dream of 

 marrying his sister, if he really believed 

 that any harm would result to the off- 

 spring; and if you could find one such 

 person could you find two — for it takes 

 two to make a marriage. 



The fact that such marriages are con- 

 tracted in spite of legislative prohibition 

 in several of our states, and in spite of a 

 considerable public feeling against such 

 unions, simply shows that there is a 

 difference of opinion upon the subject. 



The only justification for legislative 

 interference lies in the belief that con- 

 sanguineous marriages are harmful to the 

 offspring. The only justification for mar- 

 riage under such circumstances lies in 

 the belief that they are not harmful — at 

 least, in particular cases. A question of 

 fact is here involved, not mere opinion. 

 Are they harmful or are they not Or if 

 they are harmful in some cases and not in 

 others, what are the conditions under 

 which they are harmful ? These are ques- 

 tions that might well be considered by 

 your Committee on Eugenics. 



The experience of breeders of animals 

 would be especially helpful in this con- 



nection. It is extremely difficult to collect 

 statistics upon a large scale regarding 

 consanguineous unions among human 

 beings, but a breeders' association could 

 surely supply statistics concerning ani- 

 mals. We all know that the laws of 

 heredity that apply to animals also apply 

 to man ; and statistics of in-breeding 

 would be of great value if they could be 

 so arranged as to throw light upon the 

 effect of consanguineous unions in hu- 

 man beings. I understand that while 

 breeders recognize an element of danger 

 in consanguineous unions, and especially 

 in continuous in-breeding for a number of 

 successive generations, they constantly 

 resort to in-breeding to perpetuate and 

 intensify desirable characteristics. In 

 fact, it is usually through in-breeding that 

 thoroughbreds are produced; and it is 

 chiefly through the prepotency of thor- 

 oughbreds that races of domestic animals 

 are improved. If there are any condi- 

 tions under which consanguineous unions 

 would be of benefit to man they should 

 be made known, so as to enable us to un- 

 derstand, certainly, what conditions are 

 beneficial and what harmful, to the 

 end that public opinion may be rightly 

 guided in its treatment of this important 

 subject. 



We have statistics which indicate very 

 clearly that consanguineous unions should 

 not be contracted by defective persons, 

 and the results obtained by Dr E. A. Fay* 

 are specially significant in this con- 

 nection. He shows that there is con- 

 siderable liability to the production of 

 deaf offspring where a deaf-mute marries 

 a blood relative, even in cases where the 

 original deafness was not congenital. 



The statistics of the twelfth census f of 

 the United States show that at least 4.5 

 per cent of the deaf of the country, and 4.5 

 per cent of the blind are the offspring of 

 consanguineous marriages, but we do not 

 know conclusively whether consanguinity 

 in the parents produces the defective con- 



* Marriages of the Deaf in America, by Ed- 

 ward Allen Fay. Published by the Volta 

 Bureau, Washington, D. C, 1898. 



t Special Report on the Blind and the Deaf 

 in 1900. U. S. Census publication, Washington, 

 D. C, 1006. 



