Could I have come into existence and experienced my "self" if my ancestors had not been the same persons, or if a different sperm cell had coupled with my mothers egg? Would my "I" then have remained unborn or been born to a different body, maybe at a different time, or my vacancy occupied by a different persons "I"? In order for a particular "I" to be realized, must it have existed as a potential beforehand, like a lottery tickets potential for winning? Evolution and probability theory indicate that the chances for any particular individual to exist is practically zero. Have we who exist been incredibly lucky, or can our "I" be realized in some other being? If so, on what grounds is the particular potential self assigned to a particular body. I have explored several philosophical texts hoping to find something about this topic, but without success. I would be very glad if you could comment on it or direct me to some illuminating textbook or other source.
Your questions touch on several interesting and difficult issues. If you haven't already consulted it, I recommend looking at the SEP entry on "Possible Objects" . It's a somewhat challenging read, but it contains discussion (for example, in Section 2.2) of the issues you raised, and (as usual for the SEP) copious references that you can follow up. Best of luck as you grapple with this topic!