I had a wild tom that had 6 toes on all his feet. My momma cat had a litter, I have kept one. My vet finds him rare in that all his toes have bones and the claws can all pull themselves in. I guess a lot of cats have claws that don't function. My 6 toes guy has Patella Luxation, which is not common in cats at all, but i believe the cause is all the extra tendons running down the front of his back legs. He has gotten better with age, I did not want to spend $900 a knee to have him fixed. He can run and jump just fine, he just has a bit crooked legs. I had kittens from the same litter with 7 toes some feet, but there was nothing but skin and a little claw so I cut those toes off at 2 days old, beings they would be like back dewclaws on a dog and get caught and rip off. They are becoming more common, just like orange tabby females. I think its a throw back to their ancestors.