78 THE CONTROL OF LIFE 



from Galton's; it is -6244, -1988, 0630, etc. . . . 

 But tlie general idea is the same, that inheritances are 

 not interpretable in terms of the parents only, but are as 

 if the grandparents, great-grandparents, and so on, made 

 contributions diminishing in proportion to their remote- 

 ness. The law is statistical, not physiological. 



Associated with the law of ancestral inheritance is 

 the law of filial regression, which expresses the tendency 

 that the average of a character in a number of offspring 

 has to approximate to the mean of the stock. If 

 parents differ widely from mediocrity, their children 

 are not likely to differ as widely. As Galton said, " The 

 more bountifully the parent is gifted by nature, the 

 more rare will be his good fortune if he begets a son who 

 is as richly endowed as himself, and still more so if he 

 has a son who is endowed more largely." But " the 

 law is even-handed ; it levies an equal succession-tax 

 on the transmission of badness as of goodness. If it 

 discountenances the extravagant hope of a gifted parent 

 that his children will inherit all his powers, it no less 

 discountenances extravagant fears that they will inherit 

 all his weakness and disease." 



This is an important idea, that when we consider 

 numbers, not individuals, there is a notable inertia. 

 Society tends to move like a great fraternity. It is 

 not like a class in school where the elite of the class 

 press on eagerly and a long 'tail' is formed. There 

 is a tendency in society to keep up an average, and this 

 is not due to any large extent to the cutting off of the 

 laggards ; it is due to ' filial regression.* 



