Sometimes it is tough to find where a family comes from because the borders changed so much and surnames and town names often changed :)
often finding one's roots is not so cut and dry as saying you are Polish, Ukranian or Russian, because Lithuanians became Poles (Pilsudski family), Poles became Russians and so on.
For example take the case of Felix Edmundovich Dzerzhinsky ( Polish spelling Feliks Dzierżyński), the founder of the Bolshevik secret police:)
he was born into Polish szlachta "noble family" in Western Belarus, then part of the Russian Empire.