HEREDITY 483 



height are not the same, but, on the other hand, that they con- 

 stitute a distribution beginning below the parentage, and extend- 

 ing to a considerable distance above it, with the largest number 

 of individuals near the middle of the distribution, close to but 

 not identical with parental height. 



Thus the 68 children of 22 parents 70.5 inches high (row e) 

 are distributed from below 62.2 to above 73.2 inches, a range of 

 ii inches, with the greatest number (18) slightly below the 

 parental height (70.5). Any other row taken at random will show 

 the same distribution in the stature of the offspring. Heredity, 

 therefore, involves something besides the influence of the imme- 

 diate parent, which, according to all studies, seldom exceeds 50 

 per cent of the total influence of the ancestry, leaving the other 

 half to be accounted for by ancestors farther back. 1 



Not only is it true that like parents produce unlike offspring, 

 but the converse is also true, that like offspring may result 

 from unlike parents. Take any column of the table at random, 

 as column 10, containing the distribution of the 167 children of 

 the uniform height, 69.2 inches. These men of even height 

 were produced by parents ranging in stature all the way from 

 72.5 inches down to less than 64.5 inches, a range of 8 

 inches. To be sure, the parental height that produced the 

 greatest number (48) was 68.5 inches, not far from the common 

 height of the offspring (row o, column 16) and almost exactly 

 the average height of all the parents (row o, column 17), but 

 the critical study of this and all the other columns will clearly 

 show that the same kind of offspring may be produced by 

 greatly different parents. 



These facts show clearly that two sires or dams of equally 

 favorable appearance may have sprung from very different 

 ancestry. They both belong to a distribution covering a con- 

 siderable range, and if our selection is to be effective we need 

 to know everything possible of the entire group to which the 

 prospective parent belongs, or at least be intelligent as to the 

 portion of the distribution from which he is drawn. 



1 Every individual of bisexual parentage has a total of 2046 ancestors within 

 ten generations. Whether these ancestors represent that many different individ- 

 uals, or whether some are oft-repeated, depends upon the closeness of breeding. 



