Millon, Simonsen and Birket-Smith have stated that "K. Birnbaum (1909), writing in Germany at the time of Kraepelin's later editions, was the first to suggest that the term "sociopathic" might be the most apt designation for the majority of these cases.
Birnbaum proposed several subtypes of sociopathy and argued that while there may be varying degrees of 'constitutional' disposition towards disorders that could lead to maladjustment and crime, it was the effect of social forces and environments which shaped the eventual outcome.
Reviewers at the time noted different themes—a view of constitutional psychopathy as a form of degeneration with both inherited (genetic 'taint') and prenatally acquired (through injury to 'germ plasm') types, resulting in a disposition towards mental disorder or a reduced capacity to resist anti-social tendencies; rejection of the term 'inferiors' for this category; a view that emotion is central to the disorder rather than necessarily deficient intellect; description of nearly 20 subtypes of psychopathic personalities (more akin to personality disorders than psychopathy as often defined today); a pivotal role for life events and social conditions in shaping whether someone with various psychopathic dispositions would end up engaging in antisocial or criminal behavior or not, and an insistence that even lifelong criminality does not necessarily mean underlying psychopathy.
[7] By 1949, now in America, Birnbaum writes in regard to pathological Juvenile delinquency about the importance of considering both an immaturity of the personality from within, and environmental influences from without, and the complex interactions and pathways to conditions that result.
It has recently been pointed out that the distinction has generally been used to report Culture-bound syndromes in non-Western countries, despite western culture also causing its own unique forms of disorders.