My grandmother (I think) has some sort of version of IBD. She had 4 daughters and all have been healthy. Even if IBD happens to carry in every other generation your baby could be a carrier like my mom was. Which is how I got IBD.
I guess what I'm saying, is there are many things that can be passed to your child. Whether it be IBD, Diabetes or any other disease out there, you never know what your baby may be born with. I myself and my husband chose not to have kids. But, if we had we'd just ask that our babies be as healthy as possible!
There is a saying somewhere about IBD pregnancies. 1/3 get worse, 1/3 get better and 1/3 stay the same. For me, it's possible that I'd be the 1/3 that got worse because I'd had a horrible flare and I've always been underweight to boot. The healthier you are is always better for your baby!