Ageing rates vary widely
Prof Moffitt told the BBC: "Any area of life where we currently use chronological age is faulty, if we knew more about biological age we could be more fair and egalitarian." She argued the retirement age may be unfair for those "working at their peak" who then had to retire.
The researchers said it was unexpected to find such differences so early, but that the findings could help trial methods for slowing the pace of ageing and ultimately have implications for medicine. She added: "Eventually if we really want to slow the process of ageing to prevent the onset of disease we're going to have to intervene with young people."
Dr Andrea Danese from King's College London said: "I think it is surprising you can detect these changes in young people. "This is the first step to detect factors that influence the rate of ageing... very early prevention [of diseases] may be one of the things we will be able to measure better."