The exact cause of Crohn's disease remains unknown. Previously, diet and stress were suspected, but now doctors know that these factors may aggravate but do not cause Crohn's disease. A number of factors, such as heredity and a malfunctioning immune system, likely play a role in its development.
Immune System / Environmental - it is possible that a virus or bacterium may trigger Crohn's disease. When the immune system fights off an invading microorganism, an abnormal immune response may cause the immune system to attack the cells in the digestive tract, too. Or, an environmental factor may directly damage the lining of the intestines, which causes Crohn's disease to begin or to speed up. Potential factors: Substances from something eaten Microbes such as bacteria or viruses Cigarette smoke
Genetic - common in people who have family members with the disease, so genes may play a role in making people more susceptible. However, most people with Crohn's disease don't have a family history of the disease. About 10% to 20% of people with Crohn's disease have at least one other family member who also has the disease. The condition is more common in certain ethnic groups, such as Jews, and is more prevalent in Caucasians.