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It is well known that in some small European countries there exist especially favourable conditions for certain types of research which elsewhere meet enormous difficulties. This is exemplified in Denmark and other Scandinavian countries by the famous studies on the influence of genetic and environmental factors in schizophrenia, which were made possible by the exceptional availability of well organized national registers on twins, adoptees and psychotics.
Luc Ciompi (Thu,) studied this question.
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