I do not have an IBD but I am the mother of a daughter who has/had UC (she just had surgery on July 3). And her older brother was diagnosed with Crohns this past spring. These diseases come down through my side of the family although I didn't realize it until after my daughter was diagnosed. I remember that my aunt (my mother's sister) had stomach issues. My mom always said that she was sickly as a young girl and had "colitis and ileitis" (basically Crohns). Unfortunately they both passed away so the only one I can get any information from is my cousin (and we really don't speak much). And it has never been a big issue for me to find out what my aunt did many, many years ago when there have been so many advances since then.
Anyway, even though I know I technically "gave" my children IBD, it wouldn't change my mind about having them (nor my husband's mind). And this is even including having to help make the decision to watch our child go through major, life-changing surgery. We pass many genes on to our children--some good, some bad. Advances are being made everyday (maybe not fast enough for the current IBD patients). Personally, we did not play the what if game. What if we pass on the cancer gene, the asthma gene, etc. On the other side, what if we do pass on the intellect gene, the artistic gene, etc. and our children are part of finding a solution?
Good luck with your choices.