Ethnically, I am a mixed Slavic-German (~3/8 Ukrainian, ~3/8 Russian, ~1/4 German), with possible Swedish or other smaller parts. None of it matters much to me, but my ethnicity is "written" all over my face - high wide cheekbones, blue eyes, straight middle-blond hair, and stuff like that - and I am asked about it often.
Actually, I don't understand why my hair stayed blond. Both my parents were blond as children, but then their hair became chestnut brown when they were still very young, so they both had this cool dark-hair light-blue-eyes look. I waited and waited, but my blond hair became only slightly darker, till now. I thought that the blond genes were weak, like the blue eyes' genes. Well, I should be able to figure it out one day.
Most of my Ukrainian "blood" comes from my father, and most Russian (~1/4th out of 3/8th) - from my mother. Later in my life this insignificant fact played a role in a deep politics-based conflict between me and one of my parents.