A woman of A blood type and normal colour vision had five children as described (in no particular order):

Question

1. male, A blood type, colour-blind
2. male, O blood type, colour-blind
3. female, A blood type, normal colour vision
4. female, B blood type, normal colour vision
5. female, A blood type, colour-blind

Of the two men that may have had children with this woman, the first has AB blood type and is colour-blind, while the second has A blood type and normal colour vision. Which of these men is the most probable biological father in each case?

Answer 1

Woman = Blood type A, normal vision

Genotype = I^Ai, X^RX^r

Man 1 = Blood type AB, color blind

Genotype = I^AI^B, X^rY

Man 2 = Blood type A, normal vision

Genotype = I^A__, X^RY

Child 1 = male, A blood type, color blind

Genotype = I^A__, X^rY Man 1 or Man 2 could be the father, more information is needed.

Child 2 = male, O blood type, color blind

Genotype = ii, X^rY Man 2 is the father because Child 2 has type O blood.

Child 3 = female, A blood type, normal vision

Genotype = I^A___, X^RX^__ Man 1 or Man 2 could be the father, more information is needed.

Child 4 = female, B blood type, normal vision

Genotype = I^Bi, X^RX^r Man 1 is the father because Child 4 has blood type B.

Child 5 = female, A blood type, color blind

Genotype = I^A__, X^rX^r Man 1 is the father because Child 5 is color blind.