Are you Blind?

I ordered pizza tonight. When the delivery man rang the doorbell all three kids ran to the door to peek out and see who was there. I opened the door and the delivery man said "Are all of these kids yours?" I said "yes". Then he said "What's the age difference?" I said "the little ones are twins". He said "Well, it's a good thing that you gave them different haircuts so that you can tell them apart!"! Ok then.......