Shot by the Bolsheviks: A photograph of the Romanov family captured in 1913, five years before their death. Tsar Nicholas II and his wife Alexandra are in the middle, with their son Alexei. The four girls are (left to right) Maria, Tatiana, Olga and Anastasia.
The researchers linked the two new bodies to the Tsar's family by examining 16 highly-variable sections of DNA called short tandem repeats (STR) in the autosomal DNA extracted from each body, Coble said.
Every person's STR profile is a mix of their parent's profiles, allowing the technique to be used for paternity testing. The STR profiles of the two bodies were a mix of the profiles from the Tsar and Tsarina's remains, proving that the new bodies are their children, Coble said.
Mitochondrial DNA is inherited only from the mother, Coble said. The mtDNA of the new bodies matched that from Alexandra's body, and also matched the mtDNA of a living relative, Prince Philip (the U.K.'s Duke of Edinburgh), whose maternal grandmother, Victoria of Hesse, was Alexandra's sister and shared her mtDNA sequence.
Descendent in the male line
The Y-chromosome is inherited only along a father's line. The researchers found that the male body's Y-STR profile was a perfect match for both the Tsar and another living relative, Prince Andrew Andreeivich Romanov, who is descended in the male line from Tsar's paternal great-grandfather, Tsar Nicholas I.
The DNA in the remains from both graves was unusually well-preserved, Coble said, probably because the ground at Yerkaterinburg is normally frozen from September to April every year.
However, the researchers are still unable to prove which of the daughters was in the second grave, because they have no reference DNA like the Tsar's bloodstained shirt for the children.
Angela van Daal, a forensics professor at Bond University on the Gold Coast, Australia, commented that the research made great use of forensic techniques that are used in modern-day cases. "These are [now] very standard techniques," she said. "It's nice work."
