Final answer:
JK's father has the genotype AO and JK's mother has the genotype BO.
Step-by-step explanation:
In this case, the father has blood type A (genotype AO) and the mother has blood type B (genotype BO). The ABO blood types are controlled by the IA, IB, and i alleles. The IA allele encodes the A antigen, the IB allele encodes the B antigen, and the i allele encodes for no protein. Both the A and B alleles are dominant to the i allele. Since JK has blood type O, which is recessive, it means that both of his parents must have passed on the recessive i allele. Therefore, the genotype for JK's father is AO and the genotype for JK's mother is BO.