Blood Type Calculator

This works out which blood types a child can inherit. Give both parents' ABO groups and Rh factors and it lists the types that are possible and the ones that are not, without percentages, because a blood test cannot tell whether a type A parent is AA or AO. A second action takes the genotypes themselves and returns exact percentages from the two Punnett squares, ABO and Rh multiplied together as the independent genes they are. It predicts possibilities and not parentage, and rare phenotypes such as Bombay, cis-AB and weak D can break the usual pattern.