There’s no known cause of Crohn’s disease. Certain factors may increase your risk of developing the condition, including: Autoimmune disease: Bacteria in the digestive tract may cause the body’s immune system to attack your healthy cells. Genes: Inflammatory bowel disease (IBD) often runs in families. If you have a parent, sibling or other family member with Crohn’s, you may be at an increased risk of also having it. There are several specific mutations (changes) to your genes that can predispose people to developing Crohn’s disease. Smoking: Cigarette smoking could as much as double your risk of Crohn’s disease.