Ignoring the fact that you are probably not correct scientifically speaking, I think that the constitution of your descendants is figuratively, symbolically, if not scientifically, yours (please pardon my English). It's yours because you played an entirely crucial role in creating this lineage. Whatever path it took after your role in it, that path was shaped by your involvement. You don't have to believe in the spiritual importance of lineage to acknowledge that your actions, and simply being, have some important, significant impact upon it. I find this outlook a bit too modern and nihilistic for me.