As the Wikipedia article points out, John XII became pope somewhere between 17 and 25, as it seems to be unclear exactly when he was born.
Benedict IX was similarly between the ages of 11 and 20 when he became pope, which really tells you something about how little we actually know about it, since that difference should have been very notable at the time.
Benedict IX was similarly between the ages of 11 and 20 when he became pope, which really tells you something about how little we actually know about it, since that difference should have been very notable at the time.