Forgive the seemingly sophomoric question, but...
Who are you, exactly?
Or to put it another way: Which parts or facets of the universe do you identify with?
This question, so easy to ask, is all but impossible to answer in a satisfying way. If you want a hard definition, something you can feel solid and sure about — good fucking luck. Most candidate answers will be shown, with only a moment's thought, to be riddled with holes.
The longer you think about this question, though, the more you start to wonder: maybe the problem doesn't lie with any of the answers (per se), but instead with you. Maybe they're all full of holes because 'you' are full of holes.
Sure you'd like yourself to be solid, substantial, and well-defined — but perhaps you're more porous than you care to admit. Sure it'd be nice if the issue of your identity could be settled, a priori, by some ultimate metaphysical principle — but perhaps it can only be chosen, ad hoc, on the basis of moral, political, or even (gasp) aesthetic concerns.
What if 'who you are' turns out — on reflection, and at reflective equilibrium — to be largely a matter of taste? Would that be so hard to swallow?
An exploration in four parts: