In the 1950's, a young woman sued film star/director Charlie Chaplin for parental support of her illegitimate child. Charlie Chaplin's blood type was already on record as type AB. The mother of the child had type A and her son had type O blood.

Complete question:

17. In the 1950’s a young woman sued film star/director Charlie Chaplin for parental support of  her illegitimate child. Charlie Chaplin’s blood type was already on record as type  AB. The mother of the child had type A (AO) and her son had type O blood (OO).

a. Complete a Punnett square for the possible  cross of Charlie and the mother.

b. The judge ruled in favor of the mother and ordered Charlie Chaplin to pay child  support costs of the child. Was the judge correct in his decision based on blood typing  evidence? Explain why or why not. *refer to any Punnett squares to support your answer.

The judge committed a mistake in his decision. There are no chances for this couple to have a child who has 0 blood type.

Explanation:

Available data:

Cross: Charlie Chaplin x The Woman

Parental)    IAIB    x    IAi

Gametes) IA   IB       IA     i

Punnett square)    IA          IB

                      IA   IAIA      IAIB

                        i    IAi        IBi

F1)  1/4 = 25% of the progeny would have IAIA genotype, blood type A

      1/4 = 25% of the progeny would have IAi genotype, blood type A

      1/4 = 25% of the progeny would have IAIB genotype, blood type AB

      1/4 = 25% of the progeny wouldl have IBi genotype, blood type B

According to the results of the cross observed in the Punnett square, there are no chances for this couple to have a child who has 0 blood type.

Blood type 0 can only be produced by two recessive alleles i, one inherited from each parent. The mother could provide the recessive allele because she is IBi, but Chaplin could not pass to his progeny any recessive allele.

The judge committed a mistake in his decision.