It's local personalities. Like my family vote for PPP because the local PPP candidate is of the Jatt caste and a muhajir.
In our village areas, they still discriminate on the basis of caste and on the basis of whether you migrated at partition or not. Even today the mentality remains.
If the same guy stood for PTI they'd all vote PTI.
In recent general elections his vehicle was shot at by the PTI people and his guards shot and killed one of the PTI supporters. Who started it, Allah knows only, both parties claim to be victims. Anyway, after that people from our villages for a few months could not safely travel through the villages which were PTI affiliated out of fear of violent retribution. This is all inspite of the fact these villages are 15 minutes away by car, 5 if the roads weren't utter shit. People are school/college friends, attend each others weddings and funerals, but when it comes to politics, they all get very tribal.
In that situation and atmosphere, people have to stick to their "own".