A couple of things ring very off here. It is not the age difference but rather the age of the girl. She is technically still a baby.
It is not natural for a person to be attracted to babies and those that are are afflicted with a paraphilia called pedophilia. He is sexually attracted to children in a way no matter how you put it. If its not her he molests it will be another and soon he will dip younger and younger and younger as he keeps getting away with it.