Are our brains abnormal?

Are our brains abnormal? Are their any distinct anatomical brain differences in our brain that predispose us to stutter. Are they similar in all stutterers , for example if one has a specific anomaly in his or her brain that causes him to stutter , does that mean it has to be in every stutterer there is the world ? Then why do 75% of the stutterers recover and others dont ? Do those brain anomalies disappear or something ?