A STUDY OF BRITISH GENIUS. 603 



teri dei Delinquent!' and 'La Puberta") has investigated the whole ques- 

 tion of the influence of the age of the parent on the character of the 

 child. He has found that when both parents are in the same period 

 of age development elderly parents produce the highest proportion of 

 'very intelligent' children (though not the highest proportion of 'intel- 

 ligent' children). Marro has also found that, taking the fathers alone, 

 although 'intelligent' children are mostly the offspring of young fathers, 

 'very intelligent' children are mostly the offspring of middle-aged and 

 elderly fathers. He finds much the same result as regards mothers. 

 He found that the insane show an excess of elderly fathers, while mur- 

 derers show a deficiency of young fathers and a very great excess of 

 elderly fathers. The highest proportion of defectively intelligent chil- 

 dren (this harmonizing with Langdon Down's results) Marro also found 

 among the offspring of elderly fathers. Elderly fathers and very 

 young mothers were found by Marro to produce the largest proportion; 

 of 'good conduct' children, but not of intelligent children. 



