ii2 THE KALLIKAK FAMILY 



to the absence of something that would make for nor- 

 mality), we would expect in the first generation from 

 such a union all normal children, and if these children 

 marry persons like themselves, i.e. the offspring of 

 one normal and one defective parent, then the offspring 

 would be normal and defective in the ratio of three to 

 one. Of the normal children, one third would breed 

 true and we would have a normal line of descent. 



Without following the illustration further, we see 

 already that it is questionable whether we ought to say 

 that the original feeble-minded individual should have 

 been sterilized because he was feeble-minded. We see 

 that in the first generation all of his children were nor- 

 mal and in the next generation one fourth of them were 

 normal and bred true. We should not forget, how- 

 ever, that one fourth of his grandchildren would be 

 feeble-minded and that two other fourths had the power 

 of begetting feeble-minded children. We must not 

 forget, either, that these are averages, and that for the 

 full carrying out of these figures there must be a large 

 enough number of offspring to give the law of averages 

 room to have full play. In other words, any marriage 

 which, according to the Mendelian principle, would 

 give normals and defectives in the ratio of three to one 

 might result in only one child. That child might hap- 



