4 GENETICS 



Three factors acting together determine the char- 

 acteristics of an individual, namely, environment, re- 

 sponse, and heritage, as expressed diagrammatically 

 in Figure 1. It may be said that an individual is the 

 result of the interaction of these three factors since he 

 may be modified by changing any one of them. Although 

 no one factor can possibly be omitted, the student of 

 genetics places the emphasis upon heritage as the 



Heritage 

 FIG. 1. The triangle of life. 



factor of greatest importance. Heritage, or "blood," 

 expresses the innate equipment of the individual. JTt Js 

 what he actually is even before birth. It is his nature. 

 It is what determines whether he shall be a beast or a 

 man. Consequently in the diagram (Fig. 1), the tri- 

 angle of life is represented as resting solidly upon 

 the side marked "heritage" for its foundation. 



Environment and response, although indispensable, 

 are both factors which are subsequent and secondary. 

 Environment is what the individual has, for example, 

 housing, food, friends and enemies or surrounding aids 

 which may help him and obstacles which he must 



