Very interesting and I tend to agree. I always maintained that my UC was precipitated by a very short period of extreme stress. Before that, no symptoms at all. I saw blood in my stool one time, experienced severe cramping and diarrhea a week later when I was diagnosed with IBS and then hospitalized and diagnosed with UC two weeks later. I was shocked, I assumed I just had a stomach virus. No family history, no prior symptoms, nothing. I consider myself lucky, although unusual.

Yes, According to several articles I've read, there are theories that for those of us with IBD,  a genetic predisposition exists, and then an environmental trigger "turns on" the autoimmune response, resulting in a flare.

I wasn't a typical case either. I developed acute UC at age 26, shortly after picking up a very bad cold on a trip out west.  Within a week of getting sick, I was having persistent loose stools, then noticed blood within a few days.  Prior to that, I had never had any digestive problems, no IBS or similar symptoms, no family history, basically no indication that I would be predisposed to something like this.  My case was even more unusual as I had my first symptoms of UC in late May of 2005, was diagnosed mid-June, and had an emergency sub-total colectomy on July 6.  Obviously I will never know for certain, but I tend to believe that the virus coupled with jet lag was my trigger.  But chances are, given how severe my UC flare was, it probably would have happened at some point anyway, just with a different trigger. 

I believe without much doubt that my quitting smoking was my "trigger". All was fine before that and soon after I quit all hell broke loose. UC runs in my family as well so I have the freaky gene I guess. 

It has been long accepted that there are a number of triggers for that first UC flare. But, you also need to be genetically susceptible.

Jan