Interesting point Myatska.
I'm often asked the same question since I'm Polish on both sides yet am dark haired and dark eyed, looking more like an Italian than what is generally understood to be a typical blonde Pole.
I guess it has to do with the genealogical and ethnographic roots of the Polanie, or early Poles, whose ancestors would have come from further south/east, hence bringing darker complexions and features, but then they would have mixed with the fairer skinned peoples from the north/west. Hence two seemingly opposite genetic strains in the modern Pole. You can get more info if you're interested by studying the early migration of peoples across Europe from India and the Middle East (originating of course initially in Africa).