This is in chapter six of the President’s Council on Bioethics report on human cloning–it comes from a 2002 council meeting where one group of council members raised the twinning argument that JPod does, and another group responded, writing:
There are also problems with the claim that its capacity for “twinning” proves that the early embryo is not yet an individual or that the embryo’s moral status is more significant after the capacity for twinning is gone. There is the obvious rejoinder that if one locus of moral status can become two, its moral standing does not thereby diminish but rather increases. More specifically, the possibility of twinning does not rebut the individuality of the early embryo from its beginning. The fact that where “John” alone once was there are now both “John” and “Jim” does not call into question the presence of “John” at the outset. Hence, we need not doubt that even the earliest cloned embryo is an individual human organism in its germinal stage. Its capacity for twinning may simply be one of the characteristic capacities of an individual human organism at that particular stage of development, just as the capacity for crawling, walking, and running, or cooing, babbling, and speaking are capacities that are also unique to particular stages of human development. Alternatively, from a developmental science perspective, twinning may not turn out to be an intrinsic process within embryogenesis. Rather, it may be a response to a disruption of normal development from which the embryo recovers and then forms two. Twinning would thus be a testament to the resilience of self-regulation and compensatory repair within early life, not the lack of individuation in the early embryo. From this perspective, twinning is further testimony to the potency of the individual (in this case two) to fullness of form.