well right when the egg is made and in the daycare, the shininess,nature, and ability are all chosen already. so if you were to save the game before you recive the egg, then hatch it like 10 times, without saving, its always going to be the same, so chances are it wasnt RNG in the first place. Or the guy RNG but then screwed up =/
the only thing that changes in the IVs of the egg