For the blood groups in humans, the two alleles for individual's blood type is defined by three possible alleles: IA, IB, and i. With these multiple alleles, IA and IB are exhibiting codominance. This means that their respective phenotypes are expressed as long as at least a copy is present in the genotype. The allele i is the recessive allele, and an individual that is homozygous for that allele would have the blood type O.
In a possible paternity case a child's blood type was found to be type O. If the father in question has type A blood, would this exclude him as the possible father. Why or why not? What blood type would exclude him from paternity in this case?