Family Members At INcreased-risk for Developing Inflammatory Bowel Disease

First-degree relatives of people with inflammatory bowel disease ("IBD," including Crohn's disease and ulcerative colitis) have an increased risk for developing IBD themselves. This study will follow unaffected first-degree relatives (who do not have IBD) over time to understand if their behaviors, diet, and biomarkers for IBD can help predict who gets IBD and if IBD can be prevented in these high-risk individuals. Participants will be asked once per year to complete a questionnaire and have their blood, stool, and urine collected. The anticipated length of the study (registry) is approximately 10 years or longer. Parts of this study, such as the questionnaires and stool and urine collection, may be done from home, while other parts, such as the blood draw, will need to be done from Massachusetts General Hospital.