TWIN DATA ON THE GENETICS OF AGEING* 



Franz J. Kallmann 



Department of Medical Genetics, Neiv York State Psychiatric Institute, 

 Columbia University 



Despite the intricate and continuous interdependence of 

 genetic and non-genetic components of personality formation, 

 the twin study method makes it possible to appraise the effect 

 of heredity on measurable behaviour variations at all stages of 

 the human lifespan, inclusive of the senium. The technical 

 efficacy of the method is matched by its economy and versa- 

 tility as a sampling procedure, and extends to population 

 studies which call for a comparative analysis of individual 

 health and survival values. These procedural advantages are 

 most apparent in the investigation of traits requiring intra- 

 family and longitudinal comparisons under controlled con- 

 ditions, and personal contact with families from various 

 population groups, including some whose private affairs 

 might not otherwise be open to study. 



The popular notion that the adjustive and ageing patterns 

 of one-egg twins resemble each other chiefly because of 

 unusual similarity in their early environments has yet to be 

 substantiated. If confirmed, the argument would only 

 strengthen rather than weaken any correctly formulated 

 genetic theory. Psychodynamic concepts, too, are predicated 

 on the premise that man is selective in regard to important 

 aspects of his life experiences (Alexander, 1956) and takes 

 pride in being responsible for his own formula of adjustment, 

 before and during the period of senescence. 



From a biological standpoint, the process of ageing has been 



* Presented at the Third Ciba Foundation Colloquium on Ageing, as the 

 eighth consecutive report on the progress of a study which has been supported 

 by grants from the Rockefeller Foundation (1945-1951) and the Division of 

 Research Grants of the National Institutes of Health (1952-]956). 



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