Birthright.???...Birthmark???

Last Wednesday I got to substitute 1st and 2nd grade. It was great and also great to walk out at the end of the day and leave it! The Bible lesson was on Jacob and Essau and how Essau sold his birthright. Well after we talked about the story and the lessons we can learn from it, a girl with a puzzled look raised her hand. "How do you give up your birthright... isn't is like in your skin?" as she graps her own skin. Your thinking of a birthmark and then went on to explain the best I could what a birthright was, again!