All I know is that, whenever kids have come to our house over the years (not often), every cat we've had has done a runner within seconds of the kid's arrival. Even Gandolf, who was very dominant in the cat world, headed for the proverbial hills like a shot. I thought perhaps a young cat say 12 to 18 months would be more lively and therefore more able to cope with kids. I hear what you say though about choosing a cat that has already lived with children which of course makes sense.