Somewhat offtopic: I've often wondered why such profoundly (to me) disgusting foods like liver and cauliflower can be enjoyed by other people. Is this a simple matter of xyz taste receptors not showing up in certain tongues?

that is likely part of it. type "PTC" in the google search box to the right and you will see my previous posts with alluded to that.

I once saw a TV news report about a black-owned movie theatre designed around black tastes (In America). The major differences which they noted (besides AAs being more verbally active in the viewing process) were the fact that blacks eat dinner in theatres more often and that they strongly prefer fruit sodas over any other kind. It was emphasized by the fact that the owner did not bother to stock colas or lemon-lime at his theatres and pretty much only sold orange and grape.

Does any research indicate a genetic basis for alcohol dependence among North American native people?

yes.