Answer:
Yes, the mother's claim might be correct.
Please find the genotype of the parents and the cross below
Explanation:
Blood group in humans is controlled by three alleles namely; iA, iB, and i. Alleles iA and iB are dominant over allele i but co-dominant when together i.e. iAiB
Based on this, below are the blood types of an individual with the possible genotype;
Blood type A - iAiA or iAi
Blood type B - iBiB or iBi
Blood type AB - iAiB
Blood type O - ii
According to this question involving a paternity case, a woman with blood type O claims a man with blood type A whose mother is type O to be the father of her child. The woman has a genotype 'ii' while the man has a heterozygous genotype 'iAi' because his mother will contribute the 'i' allele.
Hence, using the genotype of the woman (ii) and man (iAi) in a cross as follows; ii × iAi (see attached image for punnet square), the following proportion of offsprings will likely be produced:
(2) iAi - blood type A
(2) ii - blood type O
Therefore, the woman's claim that the man is the father of her child with blood type O (ii) is most likely correct.
