Discuss how geneticists have concluded that the X-linked form of hemophilia that spread through the royal families of Western Europe and Russia in the nineteenth and twentieth centuries probably originated with Queen Victoria
What will be an ideal response?
None of the males in previous generations of Queen Victoria's family had hemophilia, but one of her sons was affected, and at least two of her daughters were heterozygous carriers. Because there was no previous history of this disorder in her family and Victoria transmitted the mutant allele to a number of her children, it is reasonable to assume that she was a heterozygous carrier. Her father was not affected, and there is nothing in her mother's pedigree to indicate that hemophilia was present in her family. It is therefore likely that Victoria received a newly mutated allele in a gamete from one of her parents.
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