As being an OC of course these are not true events or ever did happen in anything the original author of Dragon Ball made. Son Rage is the first born child of Son Goku and Chichi as a child his body had trouble with his Saiyan genes as his body tried to reject it at first which caused him to get confused his mind going blank as he became as wild as Goku when he was a mere baby. A similiar accident with a heavy blow to the head caused him to be a well-mannered boy.