As I understand, the remains of the Romanovs massacred at Ekaterinburg were identified on the basis of mitochondrial DNA, tested against that of living relatives (the Duke of Edinburgh would have matched the Czarina Alexandra and all five of her children; the Duke of Fife would have matched Czar Nicholas II), and photographic analysis (e.g. facial bone structure).

But modern molecular biology offers much more than that: the scientists who studied the remains of Ötzi the Iceman, for instance, were able to determine the deceased person's age, gender, state of health, etc. Were extensive tests along these lines performed on the Romanovs?

The reason for my asking is that I just listened to a lecture given by Helen Rappoport, who stated that genetic testing on the imperial family revealed that of the four daughters, only the youngest -- Anastasia -- was a carrier of the hemophilic gene. How exactly were the scientists able to determine this?

Of course, nobody could have know it at the time: had the Romanovs been allowed to live, and the girls possibly entered the marriage market, potential husbands would simply have had no choice but take a coin toss-type chance with them. For the good part of history, daughters of hemophilic families could not know whether they were carriers, until marrying and having children of their own (the hard way).