CHAPTER III 

 THE INHERITANCE OF FAMILY TRAITS 



Before any advice can be given to young persons about 

 the marriage that would secure to them the healthiest, 

 strongest children it will be necessary to know not only 

 the peculiarities of their germ plasms but also the way in 

 which various characters are inherited. The work of the 

 student of eugenics is, consequently, to discover the methods 

 of inheritance of each characteristic or trait. After we get 

 precise knowledge of the methods of inheritance of the 

 conunoner important traits we shall be in a position to 

 advise, at least in respect to these traits. It would seem a 

 self evident proposition, but it is one too little regarded, 

 that knowledge should precede teaching. In this chapter 

 an attempt will be made to consider many of the traits that 

 are known to run in families and to set forth, so far as known, 

 the laws of their inheritance. We shall begin with some 

 of the general characteristics of man that have been best 

 studied and then pass to a consideration of some human 

 diseases. 



In the study of many of these traits I have made use of 

 data that have been furnished by numerous collaborators, 

 chiefly on questionaires known as "Family Records." These 

 are frequently referred to in the following pages, but always 

 anonymously. The Family Records or " Records of Family 

 Traits," as they are also called, are largely derived from 

 professional circles, but not a few from farmers and business 



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