Kitz it seems to me some cats just aren't interested in hunting. I can't blame every instance of non-hunting on disability. My Buidheag, tortoiseshell moggy, 9 years old but very young with it, is a perpetual hunter always out stalking slowly, but she doesn't bring her prey back to the house, unless it is to feed one of the other cats. She would feed my 19 year old ginger tom cat, Orange aka Tiddy Puss, whom we had to say goodbye to in the new year because of continual crazy weight loss. But she did not bring kills in and play with them it eat them. She would just occasionally dump something in front of a non-catcher. She might have felt the urge to train kittens like that, I'm trying to remember. I used to see this when I was very young on the farm, old cats who stayed in the house all the time were fed by the others even though of course we fed them all.