Birth Rank and Mental Illness

Abstract

Barry and Barry¹ observed in a sample of American schizophrenics an over-representation of first borns in small sibships and later borns in large ones. On this evidence they hypothesized that the more severe pressure of parental expectation on first borns of small sibships and the relative parental rejection of later borns in large ones might contribute to the development of schizophrenia in adult life. Erlenmeyer-Kimling et al.² reported that the same trend was observed about as frequently in studies of non-schizophrenics, and Price and Hare³ suggested reasons for such a trend being present in the British population as a whole and demonstrated it in a large sample of non-schizophrenic patients⁴. They noted that the extent of the deviation varied with year of birth. They later showed that the birth rank distribution of a large sample of British schizophrenics differed significantly from that of a sample of neurotics, having the same year of birth distribution and which they assumed to be representative of the general population⁵. In sibships of two to four there was a comparative excess of schizophrenics in the later birth ranks. Hinshelwood⁶ attempted to explain this finding by postulating that, in schizophrenia, there is a specific over-representation of the penultimate birth rank. To account for the vulnerability of the penultimate sibling he revived Adler's “dethroned monarch” theory, suggesting that an unwanted last child may be an especial trauma to its predecessor. He summed data of six previous studies (four American, one Canadian and one British), and demonstrated in the total sample an over-representation of the last-but-one position. Hare and Price⁷ considered this to be a chance effect of combining studies carried out at different times and in different countries. Hinshelwood should be further criticized for combining data on patients diagnosed as schizophrenic in America and Britian. A recent patient⁸ was videotaped and diagnosed as schizophrenic by 69% of American psychiatrists but only 2% of British ones. The latest study of Hare and Price⁵ is far from conclusive for, as Barry and Barry⁹ have correctly pointed out, a sample of neurotics, or of any other non-schizophrenic patients, may well differ from the general population by birth rank distribution.