Xenia Sheremeteva provided mitochondrial DNA (mDNA) in the 1990s in order to help identify bones recovered in Siberia in 1979 as the remains of Tsar Nicholas II of Russia, who was executed in 1918 along with his wife and children. The test required a female line descendant, as mDNA is passed unchanged from mother to child, unless there is a mutation. In Sheremeteva's case, mDNA from their shared ancestor, Empress Maria Feodorovna, passed to her great-grandmother, Grand Duchess Xenia of Russia, then to her grandmother, Princess Irina of Russia, and then to her mother, Princess Irina Yusopova, and finally to her.