They could definitely have these four children. Thus, it is feasible for Sean and Catherine to have four offspring, each with a distinct blood type, if one parent is heterozygous for the A allele and has genotype iAi and another parent is heterozygous for the B allele and has genotype iBi.
Blood type is determined by the combination of alleles inherited from both parents. The ABO blood group system is based on the presence or absence of two antigens, A and B, on the surface of red blood cells. The possible blood types are A, B, AB, and O. Each person inherits one allele from each parent, and there are three possible alleles: IA (codes for blood type A), IB (codes for blood type B), and i (codes for blood type O).
Sean and Catherine, both carriers of heterozygous blood types (IAi or IBi), can indeed have four kids with different blood types. Through Punnett squares, potential combinations were explored for each child, demonstrating the inheritance of diverse alleles. Child 1 could have blood types IA or IB, Child 2 could have blood type IB, Child 3 could have blood type IA, and Child 4 could have blood type i.