I was diagnosed with pancolitis UC shortly before my 16th birthday. My husband, with left sided UC at age 45. I have two grown sons. The youngest developed sudden pancololitis at age 21. He was diagnosed within days of his first symptoms, quickly brought into remission with IV steroids, and has stayed in remission since with Colazal.
My research indicates about a 15% lifetime risk with one parent with IBD, 35-50% when both parents have it. The familial link is much stonger with Crohn's than UC.
My take away is that there is nothing you can do about the genetic risk of IBD, any more than you can change the genetic risk for heart disease or diabetes, other than to not have children. You just live as well as you can and hope for the best. Deal with things as they come up. Things generally have away of working out.
Jan