Synonyms to it may be

perchance, accidentally, as it chanced, by a fluke, by accident, by chance, by good fortune, by hazard, casually, conceivably, feasibly, for some reason, fortuitously, haply, imaginably, in some way, incidentally, maybe, perhaps, possibly, somehow, somehow or other, unpredictably, blind guess, bold conjecture, conjecture, guess, hunch, rough guess, shot, speculation, stab, suppose, supposition, surmise, unverified supposition, wild guess