Scientists from Cambridgeshire have discovered four genes that determine how fast we age.
The Sanger Institute experts were part of a group looking at DNA changes in twins. By comparing the siblings they found "age" genes that are only switched on by environmental and lifestyle factors.
Scientists already knew that "epigenetic" changes - chemical alterations to DNA made by external factors in the environment - are important to ageing. The new research goes some way towards solving the riddle of how and when these effects occur.
Researchers believe that knowing how the genes are altered could pave the way for anti-ageing drugs, although Sanger scientist Dr Panos Deloukas pointed out that the research was still at an early stage.