THE NEXT MILLION YEARS 6li 



segregation of genes. He also makes plain why too close inbreeding, 

 among those strains that possess too many hidden "skeletons in the 

 closet," is hazardous. Relatives are apt to carry the same kinds of 

 undesirable recessive characteristics, which thus have a sporting Men- 

 delian chance of joining hands and becoming evident whenever cousins 

 marry. On the other hand, recessive traits, desirable or undesirable, 

 may be carried on for an unlimited number of generations hidden 

 under the shadow of corresponding dominant traits contributed 

 through the other parent. 



This leads to the practical idea that the way to discover the genetic 

 potentialities of any individual is not simply to take account of the 

 characteristics which the person in question presents, but to observe 

 what shows up among the immediate relatives, who are presumably 

 exploiting the same general mixture of germplasm. The mother-in- 

 law joke is no joke. Every man in a eugenical sense marries all his 

 wife's relatives. 



Finally, one of the most significant contributions of biological 

 science to eugenics, which is often not appreciated even by those 

 who have heard about it, is the well-established fact of the peculiar 

 behavior of the germ cells before their union to form a new individ- 

 ual, whereby half of the hereditary potentialities carried by each 

 parent is irretrievably lost. The consequence is that the amount 

 inherited from any 'particular ancestor is not dependent upon the 

 number of generations that ancestor is removed, but upon the de- 

 vious fortunes of chance assortment and elimination of the genes 

 during the preparation of the eggs and the sperm for their union. 



The Moral at the End of the Tale 



We cannot change our individual biological inheritance. That was 

 determined for us once and for all and entirely without our connivance 

 at the time when the egg from which we developed was fertilized. 

 The cards were then dealt and all that we can do now is to play out 

 the hand. Fortunately this may be done in a variety of ways, a 

 fact that makes every individual life worth living. 



" I am the legatee of fierce desires, 



A strange bequest of sundry hopes and fears, 

 Loves, hates, and hidden smouldering fires. 

 Has come to me unsought far down the years 



