If mother 1 is a carrier of hemophilia, it is likely that her son would in fact have hemophilia while the son of mother 2 does not. Mother 1 would have the genotype XᴴXʰ, meaning she has one recessive allele for hemophilia, while the father would have the genotype XᴴY, and would neither be afflicted with hemophilia nor carry it. If you do a punnett square, it shows that the son of mother 1 would have a 50% chance of having hemophilia, since he wouldn't have a second X chromosome with a dominant allele to mask the recessive hemophilia allele. Also, if mother 2 has the homozygous dominant genotype XᴴXᴴ despite the father having hemophilia and the genotype XʰY, a punnett square for this couple proves that their son would have a 0% chance of having hemophilia. Therefore, it is very likely that their sons were not switched at birth and the correct answer is D: The fact that the father in couple 2 has hemophilia would not predispose his son to hemophilia. The first couple has no valid claim. Hope this helped!

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4 years ago