I think after all the recent studies, that Crohn's is genetic. If you have the defective genes, and then something triggers it (bacteria, virus, stress, immunizations, bad diet or a combination of all), the vicious cycle starts...
Also note that most of the defective genes they are finding related to Crohn's are also related to the immune system.... So unfortunately for us we have a defective immune system that seems to overreact or underreact in our guts, causing us this Disease...... Let's hope all the reasearch they'e doing leads to a cure.... But unfortunately I think most of the pharmaceutical companies are looking for new ways to find lifelong drugs to give us and make lots of money, instead of finding a cure......... Sorry, I think I ranted a lot.......