# 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...

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?

jerichorayel | College Teacher | (Level 2) Senior Educator

Posted on

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.