To establish a paricular type, or some specific feature, breeders sometimes breed to an animal carrying this quality.  To do so carefully can be advantageous, but to overdo the use of one or two animals can lead to genetic faults, weak kittens, and gereal loss of stamina, and even mental problems in the stock and a shortening of the life-span.  Too much inbreeding can occur when there have been only three or four cats of one particular breed imported into the country.  As cats breed fairly quickly, it takes little imagination to realise that within years the cats are being bred from first cousins, or even closer, as there is no room to move for outcrosses.
     Inbreeding is often confused with line breeding , which involves the mating of cats with common ancestors.  Inbreeding involves mating closely related cats, e.g. father to daughter, brother to sister, etc.  Such close breeding will soon emphasize good points but if there are any defects these will also show up.