Whose business is it?

Thursday morning Emilie and Elise were headed downstairs to eat breakfast. I was upstairs dressing the baby and overheard the following exchange:

Emilie said something to which Elise responded, "Its not your business." Now this probably had nothing at all to do with what Emilie said, but Em just couldn't let a comment like that pass. She responded, "It is too my business. Its not your business." This argument went back and forth for a few minutes, getting increasingly more heated as they tried to decide exactly whose business it was. Claire, who was standing by the front door in her coat watching for the bus, finally had enough. She yelled over the top of her two arguing sisters, "Your business is to eat your breakfast!" That stopped the argument dead in its tracks. Amen, Claire.