There are some real physics theories that posit the existence of infinitely many parallel universes. Look up the “many worlds hypothesis” of Quantum Mechanics. If this is true, then there isn’t just one parallel universe with one parallel set of family, etc., but rather infinitely many.

So don’t worry too much about a coming split. If the hypothesis is true, we’ve been splitting into parallel worlds constantly since the beginning of time.

If the only “special” thing that is proposed to happen on Dec-21-2012 is such a split, then it will be a very ordinary day.

As a side note, I once had a salvia experience where I was transported to one of the similar parallel universes (very common with salvia), but never came back to my “original” universe. For a day or two, everything seemed so “new”. It never bothered me, since I figured that the new universe was “close enough” to the old one! So here or there, this universe or that, this self or that one, doesn’t really matter. Each “you” is as real and as much you as any other. (Makes you wonder who “you” really are, doesn’t it?)