112 HEREDITY [ch. 



when brought up in precisely the same surroundings. 

 The same thing has been shown by an investigation of 

 school-children in relation to their home environment 

 and the habits of their parents. From a study of over 

 70,000 children in Glasgow, classified according to the 

 employment or non-employment of their mothers in 

 work outside the home, it was found that the rela- 

 tion of their height and weight to the employment or 

 non-employment of the mother was almost negligible 

 compared with the relation between the physical 

 characters of the mother and child. Still more 

 surprising, if correct, is the observation that no 

 regular relation could be found between drinking 

 habits in the parents and the health, intelligence 

 or physical development of some 1400 children in 

 the schools of Edinburgh. [Elderton, 10.] Investi- 

 gations of this kind are still in their infancy, and 

 perhaps more urgently needed than any other social 

 data — and it would be rash to make sweeping general 

 statements from the little that has been done. 

 Results like the examples quoted make one doubt 

 whether the generally accepted statements about the 

 degeneration caused by unhealthy conditions or drink 

 are really at all reliable. It is easy where insanity 

 or other disease occurs, to say that in so many per 

 cent, of the cases there has been alcoholism in the 

 ancestors, and that therefore alcoholism is a cause of 

 insanity ; but in the first place it must be shown that 



