Birth months and vulnerability to juvenile delinquency

BackgroundBirth months have been shown to affect susceptibility to schizophrenia and other mental disorders, thus this factor could also affect predisposition to delinquency through biological effects on brain development and personality and/or through relative age effects at school. This study aimed to examine the relationship between birth-season and relative age at school on the risk of delinquency.MethodsWe investigated the ratio of observed and expected births in winter/summer and that in the first/last months of the Japanese school year in 5008 young male Japanese delinquents.ResultsNo significant difference was found between observed and expected numbers of births in winter/summer or those in the first/last months of the school year.ConclusionsThe present study did not provide evidence for any effect from season of birth or a relative age effect within the school year on the risk of delinquency in Japanese male teenagers.