Sorry i cant beleive that so called downsizing alters genetic structures just like that. I was taught that you cant breed dogs without tails just by cutting tails off and then breeding from the dogs. Secondly if it was the larger brood cells that caused varroa to jump onto apis mellifera. what ever happened  to the already large Drone cells.?? one would assume that they were there all the time.
also does the size of the foundation cell determine the size of the Queen cells? i would have assumed that the bees would choose the size of Queen cell to suit their own queens.
albert cannon