Genetic therapy, person-regarding reasons and the determination of identity -- a reply to Robert Elliot

I have outlined two ways of defending the claim that there are so-called person-regarding reasons for practising gene therapy on human conceptuses. One is metaphysical and concerns our nature and identity. The upshot of it is that, in cases of most interest, this therapy does not affect our identity, by bringing into existence anyone of our kind who would not otherwise have existed. The other defence is value theoretical and claims that even if genetic therapy were to affect the identity of beings our kind, there could still be person-regarding reasons for performing it, since we can be benefited and harmed by being caused to exist or not to exist. Robert Elliot has attacked both of these lines, and my present objective is to show how his criticisms can be deflected.