What Causes Clear Leakage From The Rectum?

My husband has had a clear leakage from the rectum when relaxing in his easy chair in the evening. Not at night or during the day at the office. He is fully awake and not aware that it has occurred until he gets up from his chair and discovered his underwear wet - about the size of a small bowl. It does not smell of feces or urine, has a distinctive smell of it s own. This , of course, is troubling to him and me. Given a family history of colo-rectal cancer, we definitely want to check this out. Can you give us any information or advice. Thank you so much.