while a siamese is a short hair, there are a couple of things unique to siamese that would make it very difficult to morph a basic short hair cat body into one. the first being the unjointed kink in a siamese tail-tip, with the siamese tail also being thinner and jointed to only go up from the butt. ( this was actually bred into this fighting cat to enable storing rings on the tail and only the owner able to get them easily. )