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STUDY QUESTION Is maternal age at menarche associated with pubertal development in sons and daughters? SUMMARY ANSWER Maternal age at menarche was associated with pubertal development in both sons and daughters. WHAT IS KNOWN ALREADY Studies have shown that age at menarche is greatly inherited from mother to daughter, but it remains largely unknown to what extent age at menarche in mothers is associated with timing of puberty in sons. STUDY DESIGN, SIZE, DURATION In this population-based study we used data from the Puberty Cohort nested within the Danish National Birth Cohort. Live-born singletons aged 11 were followed from 2012 to 2016. PARTICIPANTS/MATERIALS, SETTING, METHODS In total, 15 822 children (7697 sons and 8125 daughters) gave half-yearly information on puberty from the age of 11 years until full sexual maturity or 18 years of age through self-administrated questionnaires (participation rate 71%). Information on maternal age at menarche was reported by the mothers during pregnancy. Maternal age at menarche was used both as a continuous and as a categorical variable (earlier, same time or later than peers). A multivariable regression model for interval-censored data was used. MAIN RESULTS AND THE ROLE OF CHANCE Maternal age at menarche was positively associated with timing of genital development, pubic hair development, first ejaculation of semen, voice break, axillary hair development and acne in sons, and with timing of breast development, pubic hair development, menarche, axillary hair development and acne in daughters. In sons, the associations were of similar strength for all pubertal markers, whereas in daughters, the associations were strongest for breast development and menarche. LIMITATIONS, REASONS FOR CAUTION Age at menarche was recalled during pregnancy. However, studies indicate that age at menarche is recalled moderately in adulthood. Information on puberty was self-reported, but inaccuracy of data would probably cause non-differential misclassification. WIDER IMPLICATIONS OF THE FINDINGS Early maternal age at menarche was associated with earlier pubertal development, and late maternal age at menarche was associated with later pubertal development in both sons and daughters. The largest effect-estimates were for the associations between maternal age at menarche and the daughters' age at menarche and age at breast development. STUDY FUNDING/COMPETING INTEREST(S) The study was funded by the Danish Council for Independent Research (4183-00152). There are no competing interests. TRIAL REGISTERATION NUMBER N/A.