[Xanga] A confusing case of transworld identity

Abstract: In the interests of questioning transworld identity, I outline a case of a possible world in which I, as an embryo, split into two and was born as identical twins.

I propose the following case as one where theories of transworld identity may run into complications or, in a best case, fail to explain the case adequately. I do not vouch for this case's novelty (as I have not reviewed the pertinent literature), nor its usefulness, nor the validity of my scientific description of the "facts":

Imagine a possible world where every physical fact up to one week beyond my conception is identical to the real world. However, at exactly one week after my conception, the embryo divides into two, and, instead of me being born, my mother bears identical twins. I further suppose that both twins grow to maturity, and each is genetically identical (or close enough that dissimilarities do not matter). With which twin (or both, or neither) do I have identity?

To add some complications to this account, what if I were to also imagine the following: The real-world me has an interest in martial arts, hip-hop music, and is a Christian. One of the possible-world twins, A, loves martial arts, but has no interest in rap music whatsoever. The other twin, B, could care less for martial arts, but is an avid listener of hip-hop music. One, both, or neither of them is a Christian (depending on whichever gives the most interesting account). With which twin (or both/neither) do I identify?