How can you get a twisty looking kitten when the mother cat has not sibblings around for this to happen?

A got a free female cat several years ago in the next town over. She has had kittens before about two years ago and all three in the litter where fine. She escaped from inside and got pregnant. She had three more kittens. Two have the little feet turned inward on short legs and the third one has all four feet turned inward also. From all I have read the are inbreed for that to happen but I don't have a sibling to this cat and got her in another town over. I don't know who the father is. Some neighbor cat. How can this be?