My view is basically that it came down to a quantum fluctuation. As far as we know, genuine mathematical singularities do not exist in this universe, when things become short, small or weak enough, Heisenberg (or his amendments incorporating gravity) steps in. There are still tons of problems---most of them mathematical as they cannot be empirically tested and thus fall outside the realm of science (!)---to solve before this view yields a consistent hypothesis. There are even some voices who speculated that we cannot describe Nature at these extremes because the mathematics at our disposal, in the shape of the very fundamental ZFC axions, is inadequate. The ZFC axioms make certain assumptions about the system we want to study, and there are some good, if somewhat heuristical arguments around to explain that these do no necessarily apply to the universe as a whole.
However, sometimes people succeed in doing some very remarkable things. Recently, a group of theoretical physicsists was able to construct a Universe out of quantum foam: the stuff you end up with if you quantize space as well as energy. The amazing thing: those calculations wouldn't normally yield a three-dimensional universe (rather bizarre two- or four-dimensional ones), unless you introduced a maximum velocity (speed of light) and a measure of causality... And then the foam spontaneously formed an expanding three-dimensional universe! There have been other such 'amazing!' discoveries: I vaguely recall reading up on research which managed to derive both Heisenberg's and Schrödinger's equations from the mere fact that quanta exist.
In any case, once you start reading these things, there really is not shortage to the number of ideas. Multiple universes, endless pulsating ones, universes shaped like a horn or like a soccer ball, universes curved in on themselved so that you never reach the 'edge', ... And all currently have the same status: your guess is as good as mine.
So what's yours :-)?