Biology, Brain tumours and mental disorders, behaviour and Budhism

The biologic construction of our brains leads to diferent behaviour and personalities. Like different antennas or generators, we can process signals diferent ways or receive them diferent ways. Our brain is very bad understood, and it is more evident that behavioral patterns can relate to the presence of brain tumours, or chemical unbalances. If our construction affects our behaviour, and that we were born with those, how can those people follow the Noble Eightfold Path, if their biology is made to go out of those principles. Examples, a pornstar can love sex because the hormonal level is naturally calling that need. However in other living aspects can be very compassionate. Or a good man who worked all his life get a tumour that transform him in a violent person and eventually kill someone. How can budhism "criticize" these behaviours if they are natural ocurances?