I understand that mtDNA doesn't recombine under the usual (normal) circumstances, although it may sometimes mutate.
Male germal yDNA does recombine however, so it constantly changes generationally, depending mostly on which females they mate with.
So ~theoretically~ any Human *could* possibly carry in their cells, the same mtDNA of their female ancestor from the beginning of time (perhaps 10's of 1000's, or maybe rarely even millions of years ago).
Women most often pass on to their children, the exact same X chromosome that they inherited from their own mothers. So the maternal lineage is generally preserved over generations.
The only exceptions are mutations that may occur in individuals. I suppose that some random mutations may affect most, but probably not all, of a given population of females.
Men do not pass on their father's yDNA, although they carry it in their cells in ~combination~ with their mother's mtDNA. What they pass on to their children, is their combined yDNA.
UPDATE: Lol, it's obvious genetics is not my area of expertise; however, I am at least trying to learn; and I still think I'm mostly correct about Human hybridization and certain other details of Human origins.