Can two O parents have an A or B baby in this calculator?

Under the simplified ABO model, two type O parents pass only O alleles, so the expected child ABO type is O. Rare variants and testing errors are outside the simple model.

Can two Rh-positive parents have an Rh-negative child?

Yes, if both carry a recessive Rh-negative allele. The calculator uses a simplified probability model because parent genotype is usually unknown.

Can blood type prove paternity?

No. Blood type can only suggest possibilities under simplified rules. DNA testing is required for paternity questions.

Baby Blood Type Calculator - ABO and Rh Inheritance

Estimate possible baby blood types from parents' ABO and Rh blood types using educational inheritance probabilities and Punnett-square style logic.

ABO and Rh inheritance

Blood type inheritance calculators answer an educational genetics question: which ABO and Rh combinations are possible from two reported parent blood types. Actual blood type requires laboratory testing.

child ABO = one ABO allele from each parent

ABO type is modeled from inherited A, B or O alleles.

Rh + \approx D__, Rh - = dd

The simplified Rh model treats Rh-positive as dominant and Rh-negative as recessive.

Not proof of paternity

Blood type probabilities cannot prove or disprove paternity. Use medically and legally appropriate DNA testing for paternity questions.

Important limitations

Parent blood types may be remembered or recorded incorrectly.
Rh-positive parents can carry recessive Rh-negative alleles.
Rare blood-group variants can break simple classroom inheritance tables.
Pregnancy Rh concerns should be discussed with an obstetric clinician.

Baby Blood Type Calculator

ABO and Rh inheritance

Important limitations

Frequently Asked Questions

Sources and References

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