By Fiona Macrae
Scientists have found a 'Peter Pan gene' that could explain why some people remain baby-faced while others become old before their time.
Millions of Britons are blessed with DNA that makes them look up to eight years younger than their peers.
The research - the first to definitively link genetic changes to ageing - could be why Cliff Richard and Paul McCartney look significantly younger than Mick Jagger, despite both being his senior.
Genetics could explain why Paul McCartney looks significantly younger than Mick Jagger, despite being one year older than him.
It could also pave the way for drugs that hold back the hands of time and keep hearts and brains healthy into old age.
The British-led research team made the discovery after trawling the DNA of more than 12,000 people for patterns that affected the rate their bodies aged.
This identified one stretch of DNA that clearly sped up ageing, the journal Nature Genetics reports.
Up to 7 per cent of the population has two copies of it, meaning they look up to eight years older than people of the same age. Another 38 per cent has one copy, ageing them by three to four years.
A fortunate, and fresh-faced, 55 per cent do not have it at all. Instead, they have two copies of the 'Peter Pan' gene, meaning they remain youthful-looking for longer.
The key to the study was the length of telomeres - tiny biological clocks that cap the ends of chromosomes. They get shorter and shorter with time, until eventually the cells die.
The researchers, from the University of Leicester and King's College London, found that people with the 'Peter Pan' version had longer telomeres, meaning their biological clocks ticked more slowly.