THE SCIENCE OF HAPPINESS 



In point of fact, however, no such vagueness exists. 

 The seeming obscurity results partly from the complex- 

 ity of the conditions and partly from misapprehension 

 of terms. The explanation is found in the fact that 

 heredity implies not so much the transmission of con- 

 ditions as of tendencies. 



Speaking loosely, we often say that consumption, 

 insanity, and heart disease are hereditary. Strictly 

 speaking, the statement is never true. An inherent 

 weakness or susceptibility of lungs, brain, or heart a 

 tendency towards disease of these organs may be 

 transmitted, but not the diseases themselves. And so 

 of other conditions. The word tendencies is our open 

 sesame. Two parents having qualities unlike and 

 often mutually exclusive cannot transmit these qualities 

 to their common offspring; but they can transmit all 

 their tendencies to that offspring, even though these 

 tendencies be antagonistic. 



An organism cannot be two things at once, but it 

 may tend to be many different things; antagonistic 

 tendencies within it constantly struggling for the 

 mastery. And aided by external conditions, the ten- 

 dencies at one time subordinate may at another time 

 become dominant. Failing of such favorable condi- 

 tions, tendencies may keep up an unequal and seemingly 

 inefficient struggle throughout the lifetime of an in- 

 dividual, without once making themselves manifest, 

 and yet be transmitted to the offspring with such 

 potential force as there to become operative. 



To illustrate: If one parent has black eyes, the 

 other blue, it is evident that both cannot transmit the 



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