Scientists claim the age of a girl’s mother – not her diet – has the biggest influence on when she starts her first period. A study shows genetics explains more than half the variation between women’s ages when menstruation began. Previously it was unclear how much environment and lifestyle affected the timing, and it was assumed to be a greater effect than the inherited family factor. In recent decades it has been thought the average age of menarche - when periods begin - had been falling as girls were better fed, grew faster and their bodies matured earlier.

But scientists at the Institute of Cancer Research, a college of the University of London, found a woman’s age of menarche was significantly linked with that of her relatives, including her mother, older sister, grandmother or aunts. They used mathematical modelling to find that genetic factors accounted for around 57 per cent of the variation in the age of menarche of women in the study.