A couple preparing for marriage have their blood typed along with the other blood tests. Both are AB. They ask what blood types their children may have.

Probability of A blood %

Probability of B blood %

Probability of AB blood %

Probability of O blood %

1 answer

If both parents have blood type AB (genotype I^A I^B), we can determine the potential blood types of their children using a Punnett square.

The possible alleles contributed by each parent are:

  • Parent 1 (AB): can contribute either A (I^A) or B (I^B)
  • Parent 2 (AB): can also contribute either A (I^A) or B (I^B)

The combinations from the Punnett square would be:

| | A (I^A) | B (I^B) | |-------|---------|---------| | A (I^A) | AB (I^A I^B) | AB (I^A I^B) | | B (I^B) | AB (I^A I^B) | BB (I^B I^B) |

From this, we can see that the possible blood types of the children are:

  • AB (I^A I^B)
  • BB (I^B I^B)

Probabilities of blood types:

  • Probability of blood type A = 0% (cannot have blood type A)
  • Probability of blood type B = 50% (1 out of 2 combinations results in BB)
  • Probability of blood type AB = 50% (2 out of 2 combinations result in AB)
  • Probability of blood type O = 0% (cannot have blood type O)

In conclusion:

  • Probability of blood type A: 0%
  • Probability of blood type B: 50%
  • Probability of blood type AB: 50%
  • Probability of blood type O: 0%