What are you on about? Why are you talking about DNA? Try and focus on the argument I made and resist the desire to express controversial and irrelevant theories about what causes us to behave as we do.
No, my argument does not assume the conclusion. It leads to it. That's what arguments do - they extract the implications of their premises.
Now, the premises of my argument are uncontroversial. The conclusion is alarming. But the premises are hard sensibly to deny. That's what makes it a good argument.
Here's one of my premises: we have powerful reason to avoid death, extreme unending agony aside - indeed, we have reason to avoid death even when our lives are so-so or mildly miserable.
That's not a controversial premise - not remotely. Anyone who denies it owes an argument - and their argument better have premises that are obviously true, otherwise they would be rejecting a powerfully self-evident claim on the basis of a less self-evident claim, which is dumb.
Here's another claim: the reason you have reason to avoid death under virtually all circumstances bar extreme unending agony is that it harms you. That is, it is contrary to your interests to die - extreme unending agony aside.
Do you dispute that? There's some room to dispute it - it is a more sensible premise to dispute than the previous one. For it is at least in principle possible that we have reason to avoid death for reasons unrelated to harm. However, once more, you'd need an argument. For on the face of it, death is harmful - that is, the claim that death is harmful seems no less self-evident to reason than the claim that we have reason to avoid death. Note as well that a whole range of attitudes towards another's death would be irrational if death was, contrary to what our reason tells us, not harmful.
The best explanation of why we have reason to avoid death under most circumstances is that it harms us.
Now the gravity of that harm must be immense. If we have reason to avoid death even when our lives are mildly miserable - and show no prospect of being anything other than mildly miserable - then it is clearly really harmful. And not just a one off harm either.
That's all I need for the antinatalist conclusion. For if death is such an immense harm, then it operates to make lives that feature it - that is, all lives - not worth starting.