[Significance of sibling constellations for the origin of systematic schizophrenias (author's transl)].

In previous examinations of twins the author found that, surprisingly, "systematic schizophrenias" did not occur in identical twins, whereas they did in binovular twins. Even though the term systematic schizophrenia may not be accepted, the results, in any case, remain valid because they are based on a classification that had been defined and described prior to the present investigation. From the findings in twins the question arised as to whether the constellation of siblings who are not twins might also be significant in preventing the outbreak of systematic schizophrenias. Therefore, in a sample of 500 patients examined earlier we stated how many siblings, older siblings, younger siblings, brothers, sisters were to be found in systematic schizophrenias and their special types. There were many findings, in part being statistically significant, in part suggesting, at least, that they be taken into consideration. As a result of the findings it seems clear that sibling constellations are important for the origin of systematic schizophrenias. Thus, whereas psychosocial factors proved prominent, we found the heredity rate especially low in these forms of schizophrenia.