The four girls may have all been carriers, but there is a chance that only one or two of them may have been. Not all daughters of carriers are carriers themselves.
I figured out the possible combinations and odds of each on another thread
last May. Here are my results:
The odds for each individual GD being a carrier are 50%. It's quite possible (though IMO it's not very probable) that each of OTMA inherited Alix's normal x chromosome. I stink at math, but I'll give it a shot anyway. With four girls and 2 variables, I believe there are 16 possible outcomes. If A=normal and B=carrier, here are the possible arrangements for hemophilia carriers among the girls:OTMA
AAAA - all normal
BBBB - all carriers
BAAA - Olga is a carrier
ABAA - Tatiana is a carrier
AABA - Maria is a carrier
AAAB - Anastasia is a carrier
BBAA - Big Pair are carriers
AABB - Little Pair are carriers
BAAB - Olga and Anastasia are carriers
BABA - Olga and Maria are carriers
ABBA - Tatiana and Maria are carriers
ABAB - Tatiana and Anastasia are carriers
ABBB - only Olga is normal
BABB - only Tatiana is normal
BBAB - only Maria is normal
BBBA - only Anastasia is normal
There's a 1 in 16 chance for each combination, which translates to 6.25%.
Now, say if a sufferer, like Alexei, had four daughters, ALL of them would be carriers of heomophilia
Are you sure?
I believe that's correct. All male hemophiliacs have an infected X chromosome. To produce a daughter, a father must contribute his only X chromosome -- the infected one. Hence, all daughters of a male hemophiliac will be carriers of the disease.
Female carriers (like Alix) on the other hand have two X chromosomes -- one normal and one infected. Since a mother contributes just one of her two X chromosome to produce a girl, there's a 50% chance that the infected X chromosome will be passed on.
(Female hemophiliacs are rare but possible, BTW. If a male hemophiliac and a female carrier have a daughter, there's a 50% chance that the child will end up with TWO infected X chromosomes -- one from each parent.)