Sorry I do not know how to edit my former comment, so here is my update with more text:
To answer well here, I suggest that we first have to define what is "a russian?. Looking at the birthplaces of a lot of the family ancestors of Nicholas II it is obvious that they were not often born on russian soil (of the respective periods). Peter the Great who can be considered by all possible definitions a russian (even if his mother was not a typical russian neither with her partly Tatar ancestry). Let's agree that if Peter the Great is not a russian, than what is Russian Monarchy anyhow? Peter bascialy made his Russia by bringing into positions of influence foreigners. He went even so far to basicaly eliminating his first russian born wife and their commun descendance. To replace them with a woman he discovered in the baltics and that woman was not russian and neither of nobility by birth at all. She was a simple maid and Peter who was a "real russian" Tsar made of her what he had decided. He made her his official wife and later crowned Empress of Russia after a few years and he also changed the rules of succession for her so that the daughter this couple had together may follow the father on the Throne of Russia some day. (since all their sons died unfortunately before Peter died himself). So Catherine (I "the first")will be a crowned "foreigner" on the Throne of Russia without any nobility in her ancestry.(But her husbands Peter The Great Imperial Aura was outweighting everything, to be his wife and having been raised to the Throne by him was simply enough). The fact that his wife and Empress was a born foreigner and communer was not a problem for Peter the Great and he is one of the most efficent and truely allmighty russian leaders in history. When you check the following weddings of any of the Tsarinas or Tsars to come after Catherine I, you will discover that (officialy)"Nobody" was from Russia. I mean russian slavic blood lines. There is maybe a possibility that the Tsar Paul I was (inofficialy) fathered by the lover of Catherine II the Great named "Saltykov" and not by her husband Peter who was a descendant of Peter the Great through his mother Elizabeth of Russia, the daughter of Catherine I and Peter the Great. In any case the lover Saltykov can be considered a real russian by bloodline, too. (Today DNA testing may allow to verify all this). The definition of what is a Russian is therefore not so easy when to be applied to a Tsar family member. Because for royalists this family "is Holy Russia" itself , but has (nearly) no biological roots in the population which we call the russian people. There was a famus writer "Maxim Gorki" who sympathized with the revolutionaries. He took a glass of red wine and mixed it with water as many times as he quoted "non russian" spouses or husbands.. starting with the red wine glass representing "Peter the Great". When he filled the last glass with the more and more dliluted mixture of water and wine to represent the Tsarevitch Alexej..Gorki showed.. to his friends that the water was not even pink any more.. just plain transparent water.. and he commented.. this is how much our Tsarevitch is russian today. Tsardom is first a religious belief and his position is never a matter of passport of cause, neither. More the Tsar was really powerful, like Peter the Great was truely allmighty, the decisions of the Tsar were the law. What he thought to be good was good for Russia and if he decides to make a foreign housekeeping maid become the Empress of Russia, than this is the right wise choice of the man who was sent by God on earth to reign over Russia which he considered to be backward without his reforms and massive import of foreign staff and their intelligence and manners . The Tsar Alexander II who was a very interesting good man had choosen a "real russian" mistress, who soon after became mother of several loved children. These children had a russian bloodline rooting directly in the russian population through their mother, and their father was simply.. the Tsar!. Alexander II was about to change dynastic rules in favor of these "new" family members, but the Social Revelutionary terrorists killed him with a bomb. His russian (second) wife had to leave russia with her children and Alexander III, the son of Alexander II and the (late) official Tsarina took his functions as head of state putting things back to "normal". Another non "foreign but russian" spouse of a Tsar is the wife of Mikhail Aleksandrovich Romanov (Brother of Nicholas II). It is a bit less known today that this Mikhail was a Tsar, too (the last Tsar 1918...and that he had legaly married the russian woman he loved. No matter for him that she was a communer, twice divorced and mother of a daughter and still not married with him when their first commun son was born. This good Lady will be named later: Comtesse Natalia Sergueïevna Chremetievskaïa, comtesse Brassova. Despite the 19th century dynastic rules of the Romanovs concerning the qualities such a partner had to present, the brother of Tsar Nicholas II imposed his vision of family and love on the Romanov Family and the Tsar who will later legitimize the son of his "rebel brother". I hope these informations will add some aspects about the question of "russian" partners of Tsars and Tsarinas.
