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Blood types A and B are co-dominant. O is recessive. Rh factor is determined by a different gene. The allele for a positive Rh factor is dominant over the allele for a negative Rh factor. Based on this information, could a person with O+ blood have two parents with O- blood?

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No, a person with O+ blood cannot have two parents with O- blood.

To break it down:

  1. Blood Group Alleles:

    • Blood types A and B are co-dominant which means if a person has one A allele and one B allele, their blood type will be AB.
    • The O blood type is recessive, which means a person must inherit two O alleles (OO) to have type O blood.

  2. Rh Factor:

    • The positive Rh factor (Rh+) is dominant over the negative Rh factor (Rh-).
    • A person can be Rh+ with either two Rh+ alleles (Rh+/Rh+) or one Rh+ allele and one Rh- allele (Rh+/Rh-). They are Rh- only if they have two Rh- alleles (Rh-/Rh-).

Given that both parents have O- blood:

  • Both of their genotypes for the ABO system must be OO (homozygous recessive).
  • Both of their Rh factors must be Rh-/Rh- (homozygous negative).

When both parents with the O- blood (OO, Rh-/Rh-) have children, all children will inherit:

  • OO (for blood type), giving them O blood type, and
  • Rh-/Rh- (for Rh factor), giving them an Rh-negative status.

Therefore, all offspring of O- parents must also be O- as they cannot inherit an Rh+ allele from either parent.

In summary, a child with an O+ blood type would need to receive one Rh+ allele from at least one parent, which is not possible if both parents are O-. Thus, it's not possible for two O- parents to have a child with O+ blood.