Genetics are Key to Age at Which Girls Start their Periods
13 April 2011 - Genetic makeup explains more than half of the variation between UK women’s ages at first period, according to a study of almost 26,000 UK women. Age at menarche (when periods begin) was already known to run in families; however the balance of genetic and environmental influences on this was not clear.
The age at which menstruation begins is important because it has been linked to risk of a number of chronic diseases including breast cancer. Data from the Breakthrough Generations Study – a collaboration between The Institute of Cancer Research and Breakthrough Breast Cancer – demonstrated a woman’s age at menarche was significantly correlated with that of her relatives.
Mathematical modelling showed that genetic factors accounted for around 57 per cent of the variation in the age of menarche of women in the study. Environmental and behavioural factors from sharing an upbringing or family life did not appear to have any detectable effect, while environmental factors not shared within families accounted for the other 43 per cent in variation.
