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Incomplete Dominance vs. Co-Dominance: What's the Difference?

Edited by Aimie Carlson || By Harlon Moss || Updated on October 29, 2023
In incomplete dominance, a blended phenotype appears; in co-dominance, both alleles are fully expressed.

Key Differences

Incomplete dominance and co-dominance are both non-Mendelian inheritance patterns. Incomplete dominance refers to the blending of traits, where the offspring shows a phenotype that is an intermediate of the two parent phenotypes. For example, if a red flower and a white flower are crossed, the resulting offspring might be pink. Co-dominance, on the other hand, does not result in a blend but allows both alleles to be expressed simultaneously. An example of this would be the AB blood type in humans.
Incomplete dominance is a fascinating genetic phenomenon where neither allele overshadows the other. Instead, they combine to produce an intermediate phenotype. This stands in stark contrast to co-dominance, where both alleles for a gene are equally expressed, and neither is recessive or dominant over the other. This means that in co-dominance, both traits are visible in the phenotype of the organism.
In incomplete dominance, the offspring’s phenotype is a mix of the parents. This is because neither allele is fully dominant over the other. Co-dominance is different in that both alleles are independently and fully expressed. In this case, the offspring will show both traits simultaneously without any blending.
In understanding genetics, it's crucial to distinguish between incomplete dominance and co-dominance. Incomplete dominance might be visualized as a mixing of colors, where red and white might produce pink. Co-dominance, in contrast, is like having both red and white spots on the same canvas, with both colors retaining their individuality.

Comparison Chart

Phenotypic Result

Blend of both alleles
Both alleles expressed distinctly


Red and white flowers produce pink flowers
AB blood type displaying both A and B antigens


Neither allele is dominant
Both alleles are dominant

Allele Interaction

Intermediate expression
Separate, simultaneous expression

Genetic Visualization

Mixing of traits
Two distinct traits displayed together

Incomplete Dominance and Co-Dominance Definitions

Incomplete Dominance

Incomplete dominance refers to the blending of traits.
The offspring of a red and white flower, due to incomplete dominance, might be pink.


Co-dominance is a form of non-Mendelian inheritance.
The AB blood type is a classic example of co-dominance in human genetics.

Incomplete Dominance

Incomplete dominance results in an intermediate phenotype.
If tall and short plants exhibit incomplete dominance, the offspring might be of medium height.


Co-dominance means both alleles express without blending.
In co-dominance, an individual with A and B alleles will show characteristics of both.

Incomplete Dominance

Incomplete dominance doesn't display dominant or recessive traits.
Unlike classic Mendelian genetics, incomplete dominance doesn't give clear dominant or recessive results.


Co-dominance allows multiple alleles to be dominant.
Unlike traditional genetics, co-dominance doesn't suppress one allele in favor of another.

Incomplete Dominance

Incomplete dominance showcases a mixed expression of alleles.
In incomplete dominance, the genetic outcome is a blend of both parents' traits.


Co-dominance results in distinct, simultaneous trait expression.
If two brightly colored fish breed and show co-dominance, their offspring might have patches of both colors.

Incomplete Dominance

Incomplete dominance is a non-Mendelian inheritance pattern.
In cases of incomplete dominance, you cannot easily predict offspring color based solely on parental colors.


Co-dominance exhibits two traits simultaneously.
A rooster with black and white feathers due to co-dominance will have separate black and white feathers, not gray.


Alternative form of codominance


How is co-dominance different from incomplete dominance?

In co-dominance, both alleles are fully expressed without blending, while incomplete dominance results in a mix of both alleles.

What's an example of co-dominance in humans?

The AB blood type in humans is a result of co-dominance.

What is incomplete dominance?

Incomplete dominance is when neither allele is dominant, resulting in a blended phenotype.

Can you provide an example of incomplete dominance?

A classic example is when a red flower and a white flower produce pink offspring.

Is there a recessive trait in incomplete dominance?

No, in incomplete dominance, there isn't a clear dominant or recessive trait, leading to blended phenotypes.

In incomplete dominance, are the original parental traits lost in offspring?

No, the traits combine to produce an intermediate phenotype, but they aren't lost.

Can co-dominance result in a new, mixed trait?

No, co-dominance displays both traits distinctly, without any blending.

Can an organism exhibit both incomplete dominance and co-dominance for different traits?

Yes, an organism can exhibit different inheritance patterns for separate traits.

How do geneticists differentiate between co-dominance and incomplete dominance in experiments?

By observing offspring phenotypes: distinct expression of both traits indicates co-dominance, while a blended trait indicates incomplete dominance.

Are there other inheritance patterns besides incomplete dominance and co-dominance?

Yes, there are multiple inheritance patterns like Mendelian dominance, polygenic inheritance, and more.

Are incomplete dominance and co-dominance typical Mendelian patterns?

No, both are considered non-Mendelian inheritance patterns.

Why is incomplete dominance considered a blending of traits?

Because the offspring phenotype is an intermediate mix of the parent phenotypes.

Can two organisms with co-dominant traits produce offspring with a single dominant trait?

It depends on the genetic makeup. If both parents carry the allele for the single dominant trait, it's possible.

How can one determine if a trait exhibits incomplete dominance or co-dominance?

By observing the offspring. Blended traits indicate incomplete dominance, while distinct expression of both traits indicates co-dominance.

Does incomplete dominance mask the expression of an allele?

No, it results in a blended expression of both alleles.

How can you visually represent co-dominance?

Imagine a canvas with both red and white spots, where both colors retain their distinctness.

Are incomplete dominance and co-dominance common in nature?

Both patterns occur in nature, but their frequency varies among species.

What happens if two pink flowers (from incomplete dominance) are crossed?

Typically, they produce a mix of red, pink, and white flowers based on Punnett square predictions.

Does co-dominance affect an organism's fitness or survival?

It can, depending on the specific traits and the environmental context.

Can environment influence the expression of traits in incomplete dominance or co-dominance?

While the inheritance pattern is genetic, environmental factors can influence the degree or manner of trait expression.
About Author
Written by
Harlon Moss
Harlon is a seasoned quality moderator and accomplished content writer for Difference Wiki. An alumnus of the prestigious University of California, he earned his degree in Computer Science. Leveraging his academic background, Harlon brings a meticulous and informed perspective to his work, ensuring content accuracy and excellence.
Edited by
Aimie Carlson
Aimie Carlson, holding a master's degree in English literature, is a fervent English language enthusiast. She lends her writing talents to Difference Wiki, a prominent website that specializes in comparisons, offering readers insightful analyses that both captivate and inform.

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