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Parent 1
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About

Blood type inheritance follows Mendelian genetic laws, where a child inherits one allele from each parent. The ABO blood group system is controlled by the ABO gene, with A and B being co-dominant and O being recessive. The Rh factor (Positive or Negative) is inherited independently, where Positive is dominant over Negative.

This calculator performs a Punnett Square simulation to determine the statistical probability of the offspring's blood type. It is useful for parents curious about their future child's traits or for understanding genetic compatibility issues such as Rh disease. Note that while this tool covers standard genetics, rare mutations or chimerism are excluded.

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Formulas

The probability P of a specific genotype is calculated by crossing parental alleles. For phenotype A, the possible genotypes are AA and AO. For phenotype O, the genotype must be OO.

P=Ntarget4×100%

Where Ntarget is the number of quadrants in the Punnett Square matching the target blood type. Rh factor probability is calculated separately:

Rh+ × Rh {
50% +50%
(heterozygous assumption)

Reference Data

Parent 1Parent 2Possible Child TypesImpossible Child Types
OOOA, B, AB
OAO, AB, AB
OBO, BA, AB
AAA, OB, AB
ABA, B, AB, ONone
BBB, OA, AB
ABOA, BAB, O
ABAA, B, ABO
ABBA, B, ABO
ABABA, B, ABO

Frequently Asked Questions

No. Type O is recessive (OO), meaning neither parent carries the A or B allele. Therefore, they can only pass on O alleles, resulting in an O-type child.
If a mother is Rh- and carries an Rh+ baby (inherited from an Rh+ father), her immune system may develop antibodies against the baby's blood. This condition is treatable but requires medical monitoring.
This calculator assumes standard Mendelian inheritance. Rare exceptions exist, such as the "Bombay Phenotype" or chimerism, which can mask true genetic markers.