The heterozygote shows an intermediate phenotype, such as pink flowers from red and white parents.
Neither allele is dominant; heterozygotes blend. Red (RR) x white (WW) snapdragons give pink (RW), and F2 shows 1 red : 2 pink : 1 white, so the genotypic and phenotypic ratios coincide.
Alleles are not mixed physically: they separate again in the next generation.
The heterozygote shows an intermediate phenotype, such as pink flowers from red and white parents.
Incomplete Dominance is one of the 54 topics in Genetics. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Dominant and Recessive, Test Cross, Codominance.
In humans, hypercholesterolaemia shows intermediate cholesterol in heterozygotes.
Work through the Beginner topics in Genetics first, such as Heredity, Gene, Allele, then return to Incomplete Dominance. Intermediate topics assume the Beginner vocabulary.
The closest topics to Incomplete Dominance are Dominant and Recessive, Test Cross, Codominance, Homozygous and Heterozygous. Comparing them side by side is a good way to see how the ideas connect.
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Incomplete Dominance. To practise the whole of Genetics, use the Genetics quiz.
Incomplete Dominance: The heterozygote shows an intermediate phenotype, such as pink flowers from red and white parents. Dominant and Recessive: A dominant allele shows its effect when present in one copy; a recessive allele only shows when two copies are present. Read both side by side and note what each one explains.
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Dominant and Recessive and explain the difference aloud. Finally, take the Genetics quiz and come back to this page for any question you miss.
A dominant allele shows its effect when present in one copy; a recessive allele only shows when two copies are present.
🧬 GeneticsCrossing an unknown dominant phenotype with a homozygous recessive to reveal its genotype.
🧬 GeneticsBoth alleles are fully expressed in the heterozygote, as in the AB blood type.
🧬 GeneticsHomozygous means two identical alleles for a gene; heterozygous means two different alleles.
🧬 Genetics