To answer your question...if a person can be the same person(have the same personality) or be a diff person if they cant remember their whole lifes memories.....

I would say No, because a persons memories effect the way a persons thinking becuase memories are experiences, learning and shit like that...

Example, if a persons life consists of extreme negativity, than the person has only seen negative shit and will act negative....
But, if the persons life consists of flawless positive memories, then the person will definetly, for sure have a different personality, and be a very diff. person, then the person who had only negative memories....