PARENT AND OFFSPRING 301 



In no case is the average height of the children widely different 

 from that of the parents. It is evident that children of tall 

 parents are likely to be tall, though not averaging as tall as 

 their parents, and that children of short parents are likely 

 to be short, though not averaging as short as their parents. 

 It must be understood that there may be exceptionally tall or 

 exceptionally short children in any family, and that such cases 

 are included in the averages given. 



Various other characteristics are inherited with the kind 

 of defmiteness that is shown above for height. It is often 

 supposed that infectious diseases are inherited, but with the 

 possible exception of a very few cases, this is not true. The 

 claim that diseases are inherited gains apparent support from 

 the fact that such a disease as tuberculosis may appear for 

 several generations in the same family. In case of tubercu- 

 losis the offspring may inherit a weakened body, and although 

 they do not really inherit the disease, they inherit a body so 

 weakened that the disease readily gains a hold in it. Under 

 these circumstances, constant association with those who have 

 the disease may lead to infection. 



327. Heredity and the future of the race. Few things con- 

 tribute more to successful living than a sound and vigorous 

 body, and such is a heritage of untold value. An unsound 

 body is also a heritage, but a handicap heritage. We cannot 

 emphasize too strongly the importance of making sure that 

 no avoidable tendency to disease and no abnormally weakened 

 bodies are passed on to succeeding generations. There are few 

 tragedies more awful than that of being born into the world 

 weighted down with a weakened body. Such bodies are given 

 to innocent people because parents or society did not know 

 enough or care enough to prevent the inheritance of things 

 that make successful life hard, often well-nigh impossible, for 

 the offspring. It is high time for the human race to recognize 

 and use what is known of biological inheritance. We produce 

 high types of corn and cattle because we want to make money 



