Good posture and sitting up straight might not save you from back pain because the physical condition of your spine is far more dependent on genes than lifestyle, scientists have found.
They play a "key role" in lumbar disc degeneration (LDD), for a long time suspected of being the number one cause of chronic lower back pain, according to specialists.
Over the years these discs, which cushion the vertebrae, can end up getting squashed and bulging out. Bony growths can also emerge from the spinal column itself. Both are thought to trigger back pain.Scientists have now found that serious lumbar disc degeneration is inherited in 65 to 80 per cent of cases.
Dr Frances Williams, from the Department of Twin Research and Genetic Epidemiology at King's College London, said: "The impact of hereditary factors on LDD is remarkably high. In the 70s and 80s the Scandinavians spent millions looking for all the occupations which caused back pain, but they couldn't find them."
Studies of identical twins who went into different professions - such as truck driving and being a PE teacher - showed both ended up with similarly bad lumbar disk degeneration in later life.
"Actually, the main variation is caused by genetic factors," she said.
Dr Williams has been heading a team, funded by the Wellcome Trust and Arthritis Research UK, that has found a new gene implicated in back degeneration called PARK2.
They discovered it by looking for signs of LDD in back scans of 4,600 people, and then sifting their entire genomes for clues.
Dr Williams said that, although it was early days, this approach could one day lead to new treatments.
However, the relationship between physical degeneration and long term (chronic) back pain is complicated.
Dr Williams said: "Everybody gets LDD at some point, it's like going grey. But not everybody gets back pain."
Those with more serious physical degeneration are more likely to get chronic back pain, but plenty of those whose LDD looks bad feel fine, and vice-versa.
Dr Adam Al-Kashi, head of research at the charity Backcare, said that was because chronic pain was not simply the result of physical damage.
Psychology was also important, he said, and people who had a positive outlook were less likely to suffer.
"We are discovering that pain is an abhorrent response of the central nervous system, which is controlled by the mind," he said.
While most people and doctors still assumed that chronic pain was permanent - and the best one could do was manage it - recent work suggested otherwise.
"We are finding we can reprogramme the software - the brain - to overcome chronic pain," he said.
He also argued that studies which attempted to reduce illnesses to genetics wrongly made people feel helpless.
"They think, 'What can I do?' " he said.
Dr Williams said genetic studies did not claim to reveal the whole picture, and said people should still take care of their general health to minimise the chance of back pain, in particular avoiding smoking and piling on the pounds.
She added: "Sitting up straight and exercising won't change the way your discs change, but they might help you develop good muscular strength to keep a pain-free spine and back."
Steve Tolan, a professional adviser at the Chartered Society of Physiotherapy, said: "We have little control over the genes we are born with, but we can manage how we support our backs in other ways, such as exercise.
"This can prevent an existing condition from getting worse or delay the onset of a hereditary one. The majority of people should be using exercise and a healthy lifestyle to protect their backs against future injury.
"To use an analogy, it doesn't matter what type of car you have, you still need to keep the engine maintained."
Stephen Adams - telegraph.co.uk