SYSTEMATIC study of the importance of birth order began in 1874 when Galton showed that eminent scientists were typically firstborn or only children. Since then the literature has become replete with investigations associating personality traits with ordinal position.1,2 These studies, however, have produced conflicting results, and many have come to regard such correlations with a great deal of skepticism.
The association of birth order to psychopathological conditions such as schizophrenia, delinquency, depression, and alcoholism, has also been controversial. The situation may be exemplified by the investigations in schizophrenia. The overrepresentation of latter-borns in American and British populations of schizophrenics has been demonstrated rather consistently.3-5 There is, however, evidence which indicates the predominance of older children in schizophrenic populations when small families are investigated.6 Studies done in India, China, and Japan have shown that schizophrenia is more prevalent in the eldest male.7-9 Thus, a relationship
Kayton L, Borge GF. Birth Order and the Obsessive-Compulsive Character. Arch Gen Psychiatry. 1967;17(6):751-754. doi:10.1001/archpsyc.1967.01730300111014