The family of a man with blood group AB and a woman with blood group A had three children

The family of a man with blood group AB and a woman with blood group A had three children with blood types B, AB and 0. Determine the genotypes of the parents and children. Are there, in your opinion, any doubtful facts in the problem statement?

The first blood group (0) is defined by genotype 00.

The second (A) – AA or A0.

The third (B) – BB or B0.

The fourth (AB) is determined by the AB alleles.

1) Let’s define the genotypes of the parents.

The genotype of the father is AB, the mother is A0, because one of the children has the first group (00).

Parents: AB x A0,

Gametes: A, B x A, 0,

Children: AA (second group), A0 (second), AB (fourth), B0 (third).

2) Two of the children have the third and fourth blood groups, which does not contradict the conditions, however, this couple cannot have a child with the first group, because the father has no allele 0.

Conclusion: either the third child has a different father, or he was confused in the hospital.