Most people who develop bowel cancer don't have a strong family history of the disease. Only about 5 - 10%, less than 1 in 10, cases of bowel cancer are linked to a genetic mutation that runs in some families.

So far, three types of inherited gene changes which increase the risk of bowel cancer have been found

These are:

• Familial adenomatous polyposis (FAP)
• Hereditary non polyposis colorectal cancer (HNPCC)
• MYH associated polyposis or MAP.

It is possible that in the future other genes will be identified which, together with factors such as diet, contribute to the development of bowel cancer.

Some families have more people in the family with bowel cancer than you would expect by chance but no specific gene fault is found. The greater number of cancers in these families may be due to shared environmental factors (such as diet) but may also be due to an inherited gene which has yet to be discovered.

Bowel cancer is a common cancer so if you have only one elderly relative who had bowel cancer, it is unlikely that bowel cancer runs in your family. But, you may want to talk to your GP

• if you have a close relative who developed bowel cancer under the age of 45
• you have two or more close relatives on the same side of the family with bowel cancer or cancer of the womb, kidneys, ovaries, stomach or pancreas.