Single mutations can also involve the copying or deletion of large chunks of DNA. Levenshtein would be 23 edits off, because only one event was involved in adding a single 24-segment DNA piece. This is a simple thing to calculate, but it misses some of the behavior of mutation, and so misses a bit of the picture. The more true-to-life version is more complex, more nuanced, a bit more up to interpretation, and less capable of giving a single concrete percentage.