Question

Can a child have blood group O if his parents have blood group ‘A’ and ‘B’. Explain.

Answer 1

If parents are heterozygous then child can have O blood group but if parents are homozygous then child cannot have O blood group.

Answer 2

Yes, a child with blood groups A and B can have blood group O.

If one parent's genotype is I^AI^o and the other parent's genotype is 1^B 1^o, then gametes from the parents can have either of the genotypes, i.e. I^A, 1^B or I^o.

If fertilisation occurs only between gametes with I^o, the child's genotype will be I^oI^o, and the child will have blood group O.