I have ulcerative colitis. It's one of the two diseases under the Inflammatory Bowel Disease umbrella (Crohn's is the other). I have to take pills twice a day to keep the inflammation down, and I have to have a colonoscopy every couple years to screen for colon cancer since IBD increases my risk. Mine is a very mild case that doesn't otherwise interfere with my day-to-day life. Most people aren't so lucky. Some need medications with significant side effects, or need surgery, or never get the inflammation quite under control.
IBD is largely considered to be a heritable illness. Every gastroenterologist I've met since the time of my diagnosis over a decade ago has asked if I had a family history and, when I said I didn't but that my father was an anonymous sperm donor, the doctor assured me bowel disease ran in my father's family. Therefore I was unsurprised when I learned that my paternal grandmother had colon cancer when she died. It did mean, however, that I should probably stop avoiding my regular colonoscopies the way I have been for the last several years because now I knew of two increased risk factors: the IBD and the family history of colon cancer.
My half-siblings probably know about the cancer. Our father talks to them, after all, and they actually met our grandmother, who died nearly fifteen years before I learned of her existence. But I don't know if I should tell them about my IBD. It seems awkward to bring up, but I do know if they ever go to gastroenterologists themselves for whatever reason, the intake paperwork will ask if they have any family with ulcerative colitis, among other things, and having a sibling with a disease does count as an increased risk for developing the disease yourself.
If I develop cancer, I will tell them. If they told me about their own health information, or that they were having some kind of health problems, I would be comfortable bringing it up then too. But for now, I think I will keep the IBD to myself. I'm afraid they'd think I'm weird for bringing it up. We just aren't that close.
I'd be interested to hear what other people -- donor conceived or adopted or not -- think on this topic. What would you do with this relevant-but-not-necessarily-critical information?