Questions from a four year old

Tonight a young man was baptized and, during his bedtime prayer with Isaac, Jake mentioned him. After the prayer Isaac said,"So baptism is to wash away sin. Oh, so John baptized Jesus to wash away His sins." Then Jake explained that,"No Jesus was very special and didn't have any sin." So then Isaac looked up at him and said,"So why was Jesus baptized?" Good question huh? Isaac got the simplified version of the answer, but if you're over four and want a more complete answer you can read it for yourself. Matt 3:13-15