Marion has a baby boy named Ralph. She also claims that Mr. Smith is Ralph's father. Marion is blood type B; Ralph is blood type B, and Mr. Smith is bloodtype A. Is it possible that Mr. Smith is the dad? If so what are Ralph's and Mr Smith's genotype?
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To deal with the possibility that Ralph is a son of Mr Smith, we have to deal with their genotypes and do some punnett squares of it.
Marion has a blood type B (genotype BB or BO)
Raplh has a blood type of B (genotype BB or BO)
Mr. Smith has a blood type of A (genotype AA or AO)
Now since we do not know what genotype each parent has, we have to make possible combinations.
Father x Mother
AA x BB
AO x BB
AA x BO
AO x BO
1. AA x BB will produce 100% AB offspring
2. AO x BB will produce 50% AB and 50% BO offspring
3. AA x BO will produce 50% AB and 50% AO offspring
4. AO x BO will produce 25% AB, 25%AO, 25% BO and 25% OO offspring.
We know that Ralph has a blood type of B that can have a genotype of BB or BO. Since genotype BO shows in the matching of the parent’s genotypes (2 and 4), there is a possibility that Mr Smith is Ralph's father.
Mr Smith can be the father of Ralph if and only if Mr Smith's genotype is AO and Ralph's genotype is BO.
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