I offer natural solution to actual life in real time, just type cast people hate giving up typecast same as they hate being stereotyped staying in character.
Multiple personalities come from having to assume separate social narratives for each social situation a body moves through in daily evolving socially.
Again each arriving great great grandchild will always be other peoples great great grandchild even after becoming 1 of 2 parents, 1 of 4 grandparents, etc.
Siblings that don't believe in life after death and still navigate proportionately alive as sibling, cousin, aunt or uncle, second cousin.