BIOMETRY 429 



affect the clearness of memory and judgment, the partiality of the 

 relative is a factor which can hardly be corrected and allowed 

 for." * He argued that resemblances between children of the same 

 family is as clear a proof of inheritance as resemblance between 

 parent and child in which, doubtless, he is right. 



707. It was found that, on the average, the children of the 

 same family resembled one another as closely mentally as physic- 

 ally. Pearson admits that certain physical characters such as size 

 of head and body are influenced by * nurture, food, and exercise,' 

 but since brothers and sisters resemble one another in these traits 

 in the same degree as in such physical characters as the cephalic 

 index, and the colour of hair and eye, which are not affected by 

 * home influence,' he concludes that the environment is not a dis- 

 turbing factor when calculations are made respecting the degree of 

 resemblance due to inheritance. A similar line of reasoning is 

 applied to mental characters. In effect his conclusion amounts to 

 this that if, as regards any set of characters, brothers and sisters 

 resemble one another on the average in the same degree, then all 

 the resemblances must be due to the same cause. For example, if 

 the resemblances are equal as regards geniality, probity, eye-colour, 

 hair-colour, and the cephalic index, then geniality and probity 

 must be inherited in the same sense as the physical characters 

 mentioned. " The sameness surely involves something additional. 

 // involves a like heritage from parents. The degree of resemblance 

 between children and parents for the physical characters in man 

 may be applied to the degree of resemblance between children 

 and parents for psychical characters. We inherit our parents' 

 tempers, our parents' conscientiousness, shyness and ability, even 

 as we inherit their stature, fore-arm and span." z 



708. But eye-colour cannot be influenced by environment, 

 whereas there is at least some reason to believe that geniality and 

 probity may be so influenced, and the environment of different 

 families differs greatly. Pearson meets this difficulty by the state- 

 ment that " We are too apt to overlook the possibility that the 

 home standard is itself a product of parental stock, and that the 

 relative gain from education depends to a surprising degree on the 

 raw material presented to the educator. We are agreed that good 

 homes and good schools are essential to national prosperity. But 

 does not the good home depend on the percentage of innately wise 

 parents, and the good school depend quite as much on the 

 children's capacity, as on its staff and equipment?" 3 According 



1 P. 1 80. * Loc. cit. t p. 204. 8 Loc. cit. y pp. 179, 180. 



