The authors studied a pair of monozygotic twins who became discordant for mental and physical disorders late in life. Differences in the twins' early histories, earliest memories, and reactions to the loss of their mother when they were children suggest that their early interactions with their environment resulted in different modes of adaptation, which subsequently became internalized as different defensive and characterological patterns. The authors believe that the specific environmentally determined psychodynamic influences described in the paper serve to explain the twins' discordance for disease.Abstract Teaser