One of my friends has a son with a very rare and very severe (= almost always lethal before adulthood) medical problem. Her son is otherwise a typical five-year-old boy, but he already has some physical issues which make it obvious, particularly when he's tired, that he's got something wrong with how his body moves. She gets questions about it all. the. time. from people who have no business asking - and since his condition is so rare, there's no way to just say "Oh, he's got X." So if she does explain, she has to go into the whole spiel about what X is, and people have questions, and they find out that her son is probably not going to live past his teen years, and they have more questions about that (both about the disease and about her parenting choices). My hat goes off to her - she's doing a fantastic job being a mom, and I can't imagine taking on the challenges she has. I also can't imagine how I'd stay polite to all the people who would want to ask questions about my child's condition, when their only reason for asking is just "I saw a kid walking funny and had to know why."