GENETICS OF HUMAN MIND 



411 



the L. F. and R. F. data and hence so suitable for constructing a general 

 genetic formula applicable to a wide range of families. The Leicestershire 

 data represent a relatively constant and narrow range of heredity associated 



TABLE 1 

 Grades of intellect 



Summary 



Intelligence index (percentage of high grades) 



Offspring, L. F. data 16. 5 



Offspring, R. F. data 32.6 



Expected general population 9.4 



with a variable social environment with extremes of poverty and wealth, 

 while the Royal families represent an inconstant and extremely wide range 

 of heredity associated with a more uniform social environment. Further, 



