Type O (ii) is impossible because AB parent gives IA or IB, so child always has A or B antigen.
The mystery was solved by applying Mendelian genetics and the principles of dominance and codominance. By constructing Punnett squares, it was determined that The key to solving the puzzle was identifying the unique phenotypes (specifically the AB genotype) and ruling out impossible genetic crosses (such as Family 2 having an O-type child). lab activity blood type pedigree mystery answer key