xii.] SUMMARY. 195 



kinship is so distant that its effects are not worth taking 

 into account, the peculiarity of the man, however re- 

 markable it may have been, is reduced to zero in his 

 kinsmen. This apparent paradox is fundamentally due 

 to the greater frequency of mediocre deviations than of 

 extreme ones, occurring between limits separated by 

 equal widths. 



Two causes affect family resemblance ; the one is 

 Heredity, the other is Circumstance. That which is 

 transmitted is only a sample taken partly through the 

 operation of "accidents," out of a store of otherwise un- 

 used material, and circumstance must always play a 

 large part in the selection of the sample. Circumstance 

 comprises all the additional accidents, and all the pecu- 

 liarities of nurture both before and after birth, and every 

 influence that may conduce to make the characteristics 

 of one brother differ from those of another. The 

 circumstances of nurture are more varied in Co -Fra- 

 ternities than in Fraternities, and the Grandparents 

 and previous ancestry of members of Co -Fraternities 

 differ; consequently Co-Fraternals differ among them- 

 selves more widely than Fraternals. 



The average contributions of each separate ancestor 

 to the heritage of the child were determined apparently 

 within narrow limits, for a couple of generations at 

 least. The results proved to be very simple ; they 

 assign an average of one quarter from each parent, 

 and one sixteenth from each grandparent. According 

 to this geometrical scale continued indefinitely back- 

 wards, the total heritage of the child would be 



2 



