Blood types A and B are dominant traits and type O is recessive. The percentages given in the first column of this chart represent the odds that a child born to parents with the specified combinations of genotypes will have the genotype given in the second column. Note that each of the four blood phenotypes can be the outcome of at least six parental genotypes. Complex as this may seem, it is actually a very simple example. Most inheritance patterns are additive, not dominant/recessive, and even for blood types, many other factors (e.g., Rh negative or positive) may be part of the phenotype.
| Genotypes of Parents* | Genotype of Offspring | Phenotype | Can Donate Blood to (Phenotype) | Can Receive Blood from (Phenotype) |
|---|---|---|---|---|
| AA + AA (100%) | AA (inherits | A | A or AB | A or O |
| AA + AB (50%) | one A from | |||
| AA + AO (50%) | each parent) | |||
| AB + AB (25%) | ||||
| AB + AO (25%) | ||||
| AO + AO (25%) | ||||
| AA + OO (100%) | AO | A | A or AB | A or O |
| AB + OO (50%) | ||||
| AO + AO (50%) | ||||
| AO + OO (50%) | ||||
| AB + AO (25%) | ||||
| AB + BO (25%) | ||||
| BB + BB (100%) | BB | B | B or AB | B or O |
| AB + BB (50%) | ||||
| BB + BO (50%) | ||||
| AB + AB (25%) | ||||
| AB + BO (25%) | ||||
| BO + BO (25%) | ||||
| BB + OO (100%) | BO | B | B or AB | B or O |
| AB + OO (50%) | ||||
| BO + BO (50%) | ||||
| BO + OO (50%) | ||||
| AB + AO (25%) | ||||
| AB + BO (25%) | ||||
| AA + BB (100%) AA + AB (50%) | AB | AB | AB only | A, B, AB, O (“universal recipient”) |
| AA + BO (50%) | ||||
| AB + AB (50%) | ||||
| AB + BB (50%) | ||||
| AO + BB (50%) | ||||
| AB + BO (25%) | ||||
| AO + BO (25%) | ||||
| OO + OO (100%) AO + OO (50%) | OO | O | A, B, AB, O (“universal donor”) | O only |
| BO + OO (50%) | ||||
| AO + AO (25%) | ||||
| AO + BO (25%) | ||||
| BO + BO (25%) | ||||
|
*Blood type is not sex- |
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A-