Scientists: Adolescence now lasts from 10 to 24

Young people are also getting married and having children later.

According to the Office of National Statistics, the average age for a man to enter their first marriage in 2013 was 32.5 years and 30.6 years for women across England and Wales. This represented an increase of almost eight years since 1973.

Lead author Prof Susan Sawyer, director of the centre for adolescent health at the Royal Children’s Hospital in Melbourne, writes: “Although many adult legal privileges start at age 18 years, the adoption of adult roles and responsibilities generally occurs later.”

She says delayed partnering, parenting and economic independence means the “semi-dependency” that characterises adolescence has expanded.