If you think that the stereotypical “Ivanov, Petrov, Sidorov” are truly Russian family names, indicating ethnicity to the Muscovites, then you may be surprised to learn that these were often family names from the names of the noble masters that were given to the lord’s serfs, when it became necessary for the serfs to have family names. So such homegrown Nazis, from former serfs, in fact, can never know who their ancestors were in reality, and not as they thought up for themselves. It’s hard to trace your lineage when your great-great-great-grandfather’s family is traded for a sack of grain or a new dress.
In addition, the empire also imposed its version of family names on those who were not even serfs – in order to become a noble, in this state people were forced to change their family names or invent new ones, because “non-Nazis” did not allow people with “non-standard” family names to receive noble title.
And the occupied peoples of Siberia (even those that did not fall under serfdom) were still given last names “at random”, so now you will often meet, for example, among the Sakha people Ivanov, and Petrov, and Sidorov.