Siameses cats tail - feature of the breed

   I have a Siamese cat with no tail, ie there is a little bit, like a stump.It is the sort or defect? The tail is not round but flat, like a belt and is very short, sometimes it becomes round and fluffy.
   Perhaps you have a very rare breed of Thai bobtail. In this breed all siameses cats, short tails.
  Siameses cats kittens. In three short tail with a kink, one with a normal tail. What is it?
   This is a tribal marriage, both siameses cats parents are carriers of recessive creases in the tail. A couple should be disbanded.