Look at what I just read in Stanford Encyclopedia of Philosophy: "2. You could
Interesting question. Can't we interpret the story you told as one in which you never exist but someone quite similar to you does instead? Why would such an interpretation be unreasonable?
You list six conditions that you seem to regard as jointly sufficient for someone's being you: (1) having exactly your DNA sequence; (2) being born on your birth-date; (3) being told that your parents are his parents; (4) being given your name; (5) your parents' having no biological child; (6) all else being equal.
None of those conditions is individually sufficient for someone's being you. (1) Given identical twinning or cloning, someone else (your twin or clone) could have exactly your DNA sequence; (2) plenty of other people share your birth-date; (3) someone else could be told that your parents are his parents (and has been if you have a brother); (4) someone else could (and may actually) share your name; (5) your parents' having no biological child is certainly not sufficient for someone's being you; (6) ditto for "all else being equal."
So why think that when we combine (1)-(6) we get you? What is it about the combination that forces us to regard the result as you?