Genetic and gender influences on nocturnal bladder control--a study of 2900 3-year-old twin pairs

OBJECTIVE: The present study of over 2900 twin pairs born in England and Wales in 1994 examines the influences of genetics and gender on nocturnal bladder control at 3 years of age. MATERIALS AND METHOD: Parent report data was analysed in terms of means and components of variance, using a sex-limitation model to explore genetic and environmental variation within and between the sexes. RESULTS: Both genetics and gender are seen to influence acquisition: bladder control at 3 years is moderately heritable (24%), and girls show on average slightly increased acquisition compared with boys, even within opposite-sex pairs. The sex-limitation modelling showed an interaction between genetic influence and gender whereby nocturnal bladder control was significantly more heritable in boys (33%) than girls (10%). CONCLUSIONS: Both genetics and gender are important and interacting factors in the aetiology of nocturnal bladder control.