All identities are social constructs (not just national ones - class, gender, sexual orientation, political, etc.). But just because I realize that doesn't mean that I don't have any (and we all have them). Objective truths are assembled and understood through the lens of various values to create those identities. There is no one Polish identity. Mine is largely that of the liberal intelligentsia and really bears little resemblance to the national identity of the folks I speak of above. I feel on some level a sense of collective shame at various acts of repression and discrimination committed in Poland's name, e.g. against the Ukrainians. Those events and policies are objective facts, my understanding of them is on one level a combination of my values and my national identity, on another a constitutive part of that identity, a reflection of a collective understanding of what being Polish 'means'. Someone with a different Polish identity will understand various objective facts in a completely different manner.

Virtually everyone in Europe and the US has some sort of national identity, and that includes those who dislike the whole category. Take DoDo for example, his feelings about Horthy or Kossuth are, I am certain, of a different nature than about Antanas Smetona or Garibaldi. On the other hand a few centuries ago most Europeans had no such identity. National identity is a relatively new phenomenon. At the same time most had some sort of estate consciousness, most don't now.