Grabbing His Cane

I also think that Gregory outgrew idiolizing his dad, like all the kids had to in a military base. Did you notice that the happy Gregory was 8 (birthday candles), and so imo, when growing up, reading, learning, and experiencing, and being able to have an idea of his own, he realizes he does not agree with his dad, and the dad reacts to that loss of adoration by force and abuse, etc.
I think the ice-cream scene, and the look Gregory has in his eyes, of complete idolization is important, because this is exactly what House cannot have, he find flaws in everything that seems perfect, because, maybe, the first think he idolized turned out to be a pretty crappy thing!