Nobody's ancestry is monolithic, we are all mixed to some degree. However, I would say that compared to other countries, we definitely fall into the category of being more mixed than others. To dumb it down for you, Pakistan is pretty much just a mix of Afghanistan and India. As a result, the two major groups of people in Pakistan are the Indics and the Iranics.
However, being wedged right in between Central Asia, the Middle East, North Asia and South Asia means many others have come to our region as well, but these groups have pretty much entirely assimilated into either the Iranic or Indic (some of them even both) fold. But a few of them have retained their unique identity (such as the Hazaras, Burusho, Sheedis and Kalash).
In terms of individuals, because of these above facts, we all tend to be very mixed, but usually identify with our patrilineal clan, which is the continuous chain of male ancestors on our fathers side (so basically our father, his father, and his father before him, going on for as far back as we can remember).
But of course, that's only in terms of ancestry. Most Pakistanis identify more with being Muslim than belonging to a specific set of people with a recent common ancestor (even the less religious tend to hold such views). This is because of the fact that in Islam, loyalty to Muslims as a whole is considered a vital aspect of the religion and because as per Islam, all of humanity shares a common ancestry going back to Adam (peace be upon him) and Eve (may Allah be pleased with her). So you'll get people who aren't descended from the Islamic invaders but still view them as their heroes. But the trend of ethnocentrism is growing among Pakistanis, but due to how mixed we are a lot of us are struggling to find a coherent narrative based along these lines.
j-31 
