I think that might be true. I was in the army with a 100% native American. For the most part he was quiet and unassuming and never drank until one night he went into town and got drunk. When the taxi dropped him off at our barracks, he proceeded to start kicking in the car door then when he got upstairs to our floor, he then pounced on the guy who was sleeping in the bunk next to his and started beating on him.........
We broke them up and had to subdue Kai until he settled down. The next day he had no memory of what happened the night before and he never went drinking again.
It is theorized that cultures which did not settle in cities also did not propagate the tolerance for alcohol which enabled urban populations to avoid much water-borne disease.
I worked with an American Indian man and one day our company had a dinner to celebrate something. Beer was served and after two or three he began to throw the small packages of butter across the room and in general make an ass of himself.
A few days later, I talked to him and he had no memory of what he did.
But then, I also worked with a white man from Georgia who went fishing, got drunk, fell in the creek, lost his fish, shot up his ammo, tried to kill a local black man, arrested by the sheriff, released and had NO memory of what happened, until he got drunk again. That was when he told me the rest of the story. He was very dangerous when drunk.