It's real. My friend has a cat like that. Whenever I'm at her place it always makes me laugh when it's chasing toys around.
Its a genetic defect that breeders to and keep dominant, i think its a bit fucked up to be doing something like that.
I agree. Same with Scottish folds, but I doubt they're as hindered by it. But I suppose in general there are many less cat breeds than dog breeds with mutations breed in... I'm ok with is polydactalism though - those cats seems to be fine with their condition (and it seems a lot of strays have them - maybe it aids in hunter and getting around in the snow).