That's why it is important to teach your kids at a very young age, even when they are just 5 years old, or whenever they make comment or tell their siblings/friends that they are stupid or fat or anything bad, that it is hurtful for the other person to hear those words and ask them what would they feel if someone else will call them that! I have 14 nieces and nephews and 8 grand nieces and nephews (I dont have children of my own as I am not married), but kids will always remember what you tell them. Some of them will never say it again but some needs longer time to remind them over and over again.