In order to get sick with IBD (crohn's or ulcerative colitis) you must be genetically predisposed and then it has to be triggered...
stress is not proven to be a trigger, it is thought to be an exacerbater of symptoms once one is sick with it...however I know I was under a tremendous amount of stress when I got sick, but I did have the signs of perianal crohn's skin tags in my early teens (which was sluffed off as hemmies) and didn't get sick internally until my early 20's during the time of high stress so I wouldn't be surprised if stress was a trigger because that's how it played out for me...just because it's not a proven trigger doesn't mean it's not...much needs to be learned about
According to Dr. Kevin Rioux from the university of Alberta...
It's estimated that if one parent has IBD (either CD or UC) their offspring has a 10- to 15- fold increased risk of developing IBD (either CD or UC) compared with those who do not have a parent with IBD.
Smoking, including second-hand smoke is one KNOWN environmental trigger.
A significant percentage (~20%) of IBD patients have a relative that also suffers from IBD.
Certain ethnic groups are at substantially higher risk for IBD than the general population (mostly those of jewish descent).
There are extream cases of familial IBD where nearly every member of a family suffers from the disease.
In studies of identical twins, if one twin has crohn's there is a 40-60% chance the other twin will also have the disease.
My bum is broken....there's a big crack down the middle of it! LOL :)