If you breed brother and sister cats to many times you will get a twisty cat. A twisty cat is a cat that thats front pawsare bent and it is very hard for them to walk and sad to watch. My cat is a twisty cat and was breeded to many times and almost died but my mom saved him from an SPCA. He has one lung smaller then enough and his heart beats faster then a normal cat. It is unfair to the animal. I wish somethings were not as hard and he could be a normal cat but he can't because of people who think breeding is fun.