Poles are very racially mixed, as are all humans.
In pre-history humans trekked the world both with seasonal migrations and long-term, long-distance movements.
You've got to bear in mind that humans didn't make it the Americas by hopping on a plane from Addis Adaba to LA - they walked to the Bering Strait about 18,000 years ago after spending 150,000 years elsewhere.
100% Polish - what does that mean? Racially, it means your racial mix may or may not be similar to people in your geographical area (do you really know your family 20 generations back?) - but that still means you are racially mixed, doesn't it? Let's face, you're probably part Albanian,Armernian, Georgian, Turkic, East Asian, Arab, south Asian and Native American as well as north European acclimatised to relatively sunless living - hence your pale skin to maximise vitamin D absorption.
If you like blondes, just say so - but go easy on the racial stuff, it really has been debunked by advances in mitchondrial DNA testing.