I don't think they're genetically unable to stop, but I think they're genetically predisposed to prefer eating meat if it's an option. I've gone without dairy for a couple of months here and there (while traveling in Asia where it's much less of a thing than at home) and definitely still missed it by the time I got home.
Also commercials and just society around you influences your cravings. I think if you would grow up somewhere where there is no dairy for example, you would not crave it.