Incomplete Dominance Calculator
Model genetic crosses where the heterozygous genotype results in a third, blended phenotype (e.g., crossing red flowers and white flowers yields pink flowers).
Alleles & Parental Genotypes
Customize your alleles and phenotypes, then select parent genotypes.
Incomplete Dominance 2×2 Grid
| R | W | |
|---|---|---|
| R | RR | RW |
| W | RW | WW |
Trait Probabilities
Genotype Ratio
Phenotype Ratio (Blended)
Intermediate Blending
In incomplete dominance, heterozygous offspring exhibit a blend of parent phenotypes. For example, crossing Red (RR) and White (WW) flowers produces Pink (RW) flowers.
Incomplete Dominance Cross Reference Table (Snapdragon Example)
| Parental Cross | Offspring Genotypes | Red Phenotype % | Pink (Blended) % | White Phenotype % |
|---|---|---|---|---|
| Red × White (RR × WW) | 100% RW | 0% | 100% | 0% |
| Pink × Pink (RW × RW) | 25% RR, 50% RW, 25% WW | 25% | 50% | 25% |
| Pink × Red (RW × RR) | 50% RR, 50% RW | 50% | 50% | 0% |
| Pink × White (RW × WW) | 50% RW, 50% WW | 0% | 50% | 50% |
Calculation Methodology & Biological Principles
Pigment Concentration Blending
In incomplete dominance, a single functional allele (R) produces half the quantity of pigment compared to two functional alleles (RR), yielding an intermediate (Pink) color.
1:2:1 Genotypic & Phenotypic Equivalence
Crossing two heterozygotes (RW × RW) produces 1 RR : 2 RW : 1 WW, which directly maps to 1 Red : 2 Pink : 1 White (1:2:1).
Frequently Asked Questions
What is Incomplete Dominance? ▼
Incomplete dominance is a form of intermediate inheritance in which one allele for a specific trait is not completely dominant over the other, resulting in a blended, intermediate phenotype in heterozygous offspring.
How does Incomplete Dominance differ from Complete Dominance? ▼
In complete dominance, the heterozygous individual displays the full dominant phenotype (e.g. Aa shows dominant trait A). In incomplete dominance, the heterozygous individual exhibits a mixture or blending of both parental traits (e.g. RW yields pink flowers).
What are classic examples of Incomplete Dominance? ▼
Snapdragon flower colors (red RR × white WW = pink RW), Andalusian chicken feather color (black × white = blue/grey), and hair texture in humans (straight × curly = wavy).
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