A couple has just learned that their daughter has hemophilia. They already have a son who does not have the disease. What are the genotypes of the couple? Explain your reasoning.
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The gene for hemophilia is sex-linked, a recessive on the X-chromosome. The daughter must have both Xs with the gene, while the son does not have the gene on his X chromosome.
Where do I go from there? Please help me I'm having a very hard time trying to understand this
Since the son gets the X from mom, she is heterozygous for that gene, a carrier.
The daughter has to get XX, both with hemophilia, one from each parent. That must mean that dad has hemophilia too.