Dave,
- If your Dad hadn't existed during the same time as your Mom, your self could never have existed -- but that particular combination of sperm cell and ovum would still have represented a person -- you.
- Your Dad probably produced about a sextillion sperm cells in his life time (interesting coincidence). Your Mom probably came with about 500 ovum. You are here because your specific sperm cell got together with your specific ovum. If you have 2 siblings, the likelihood of you ever existing -- given OOFLam, and that your Mom and Dad had intercourse -- is only (1+2)/500,000,000,000,000,000,000,000.
- What I'm claiming is that the 500 sextillion combinations of sperm cells (from your Dad) and ova (from Cleopatra), still represent different selves though none of them really had a chance to "actualize."