I know, I know it seems a fricking obvious difference but bare with me!
My cats had been housecats in that they had litter trays and spent their entire time indoors but we had somoene move in four doors down with four Simaese cats. These cats come into our garden and shout at our cats through the windows (sometimes in the middle of the bloody night) and since then my cats are desperate to get otu and chase them off. So they keep escaping and then come home again. So what percentage of time do they need to leave the hosue to be described as 'normal' cats... or is the fact that they go out at all a sign they are no longer housecats? Prior to these Siamese they would occasionally go into the garden but never venture any further. One of the cats still refuses to go out at all, but she was the previous feral cat and I think she is too frightened to g o out.