Paetkau was my Grandfather's Mother's (mY great grandmother) last name. So for me, it is a ethnic Mennonite name. Earliest Mennonites are followers of Menno Siemens teachings and he was from the Friseland area, So the origination most likely was Dutch. Mennonites, tended to marry other Mennonites and so a lot of the last names are repetative but not the same family lines) ) and so because of religious persecutions they migrated into Germany and settled there for a long time, so it could be classified as German....but that's only if they intermarried with local Germans, right? But they really didn't do that whole total integration thing. However, they spoke German, and lived in Germany. Many of these "German" Mennonites migrated again into the Ukraine area from an invite of Catherine the Great. There was a huge community of their "colonies" in the Ukraine . (They settled and thrived there until their livelihood was threatened in the early 1910-1920's due to the revolution from which many Mennonites fled or migrated - Including my Grandparents - but my Great Grandparents stayed behind - to N and S America and pretty much anywhere BUT Russia because of the anarchist Nestor Makhno was waging a ethnic cleansing aimed directly at them in particular with his Black Anarchist Army..... and it was brutal. The ones who couldn't escape Russia, had a horrific existance. A small community remains from those who survived the gulag or Siberian exile) So are they German? Or Ukrainian? I think it's safe to say that Dutch is where it all started and most likely where the name originated from... but as for ethnicity, I would also say the Mennonites are an ethnicity unto their own (being ethno-religious much like the Jewish people are) due to not a whole lot of integrating and a whole lot of Mennonites marrying other Mennonites - so it could be classified as Mennonite as well..