If you feel a bit of a wuss compared to others when it comes to tolerating pain, you can blame your parents.

Experts say they have discovered why some people are more sensitive to pain - it's in their genes.

Scientists came across the gene while studying 578 people with osteoarthritis - and found it also existed in patients with sciatica, phantom pain, back problems and pancreatitis.

Experts then tested the pain threshold of a group of healthy women and found that those who had the same gene were more sensitive to, and less able to tolerate, pain.

Researchers say the key lies in a protein made by the mutated version of the gene, known as SCN9A, which stays open longer than the normal one. This, they say, increases the activation of nerves that produce sensations of dull, aching pain.

Experts are hoping the discovery will lead to the development of new treatments for people suffering from chronic pain as Dr Geoffrey Woods, of Cambridge University, explains: "The search for effective analgesics (pain relieving drugs) with acceptable side effects has long been the goal of doctors and biomedical researchers.

"Because current therapies have limited efficacy, with up to 50 per cent of treated subjects receiving inadequate pain relief, there exists a significant need to develop better therapies."

Doctors are now hoping that drugs can be developed to modify the protein's activity, leading to more effective painkillers for those with the gene.

Medical geneticist Dr Woods said: "As a sense, pain serves as an adaptive mechanism that protects us from tissue damage by alerting us to events that are capable of producing injury and evokes behaviours that promote tissue healing.

"However, the development of maladaptive persistent pain states in response to tissue injury is common, with one in six adults suffering from a chronic pain condition

"As individuals appear to have differing genetic susceptibilities to pain, future studies should be directed toward understanding whether responsiveness to different classes of analgesics is also genetically determined", he added.

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