This is the hallmark of a robust biological system: political parties can perish in a tragic accident and the society will still run, sometimes with little more than a hiccup to the system. It may be that for every strange clinical case in which brain damage leads to a bizarre change in behavior or perception, there are hundreds of cases in which parts of the brain are damaged with no detectable clinical sign.
David EaglemanThe drives you take for granted ("I'm a hetero/homosexual," "I'm attracted to children/adults," "I'm aggressive/not aggressive," and so on) depend on the intricate details of your neural machinery.
David Eagleman