The fact that some people can be born with 6 fingers doesn't mean that saying "a human hand has 5 fingers" is generally false.
replyIt also means you can't use the generalization "a human hand has 5 fingers" to then say that "therefore because your hands have 6 fingers, you are not a human"
replyI the sense of what OP did say, it would be more "grafting a sixth finger doesn't mean that you are not human anymore".
replyJust like taking meat from your arm to create new genitals doesn't make you a man, biologically (psychologically it may be different).