Oh sorry i forgot to say, that our one cat, toto who died, was desprate to go out, always crying to get out and it was cruel to leave him in, so we had to let him. He was a cat on his own, now we've got 2 kittens. There too young really but its only my opinion, but 2 cats seem to me to be more content with staying indoors, i think it might be to do with always having company and someone to play with. Only in general of course i dont believe it to be the same for every single cat.