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Having observed these cats, I think the problem is behavioural. They are slim and sleek but apparently have some siamese in them, and having got a hold of them you can't feel their spinal bones and ribs as you can with underfed cats. They were apparently removed from their mother at 4 weeks old which is much too young in my opinion, they haven't had enough maternal input to teach them their manners when eating. Also, when they were tiny kittens they were only fed twice a day on ordinary, not kitten food. I think they have learned that they have to gobble up anything they can get their hands (paws!) on just in case that's the last they get. Their owner told us he had been thinking of getting rid of them if they didn't stop jumping around. They are not cruel people but I really don't believe they have any understanding of how to look after cats. They are put out in the morning, whether they want to go out or not, and are out until late at night. It makes us wonder really why they had them - they were very cute as babies and their kids were full of them, but now they don't seem very bothered.