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Regina Bailey

What is Incomplete Dominance?

By September 29, 2007

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Incomplete Dominance is a type of inheritance in which one allele for a specific trait is not completely dominant over the other allele. This results in a combined phenotype (expressed physical trait).

For example, if you cross pollinate red and white snapdragon plants, the dominant allele that produces the red color is not completely dominant over the recessive allele that produces the white color. The resulting offspring are pink.

Learn more about genetics:


November 26, 2007 at 5:10 pm
(1) Adrianne says:

Actually the definition you provided is for co-dominance. In incomplete dominance the trait of the dominant allele is diminished because of a mutation and therefore if paired with a recessive trait the dominant trait will be muted. This still results in a pink color because muted red is pink, but the mechanism is different.

February 9, 2008 at 1:13 pm
(2) bob says:

boo ya totaly awsome

October 19, 2008 at 7:30 pm
(3) t. heck says:

adrianne you are wrong. what is written above is correct.

October 28, 2008 at 6:37 am
(4) lol says:

bio sux

November 17, 2008 at 11:42 pm
(5) lol girl says:

t.heck is so right

November 19, 2008 at 11:28 am
(6) cellie says:

agreed, the above is correct, just finished me homework- gratzi! ^_^

March 17, 2009 at 3:02 pm
(7) Hope says:

Bio doesnt suck, and the definition above is correct.
incomplete dominance- situation in which one allele is not completely dominant over another.

Codominance- situation in which both alleles of a gene contribute to the phenotype of the organism.

March 21, 2009 at 3:15 pm
(8) potatoes says:

woooooooooooooooooooooooooow didnt understand a word u just said so it must be right weeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee…………………………………………………………………………………………………

May 20, 2009 at 8:29 pm
(9) anna says:

Adrienne is right.

July 13, 2009 at 12:21 pm
(10) chandra says:

what you have provided is the definition for co-dominance, the correct definition for incomplete dominance is when the dominant allele does not completely maskthe effects of the recessive allele in the heterozygote.

July 20, 2009 at 2:16 pm
(11) Court says:
July 28, 2009 at 10:46 am
(12) Greencake says:

Im doing bio-med at uni, definition is correct

September 2, 2009 at 5:46 am
(13) max says:

Wow thanks for the answers biology rules!!!!!!!!!!!!!

September 6, 2009 at 1:45 am
(14) Kirsty says:

Thanks Court your answer has cleared up my biology homework =)

January 1, 2010 at 3:14 pm
(15) thishana says:

thank you but i don’t know how to do punnett square its really hard and what is genotype, hetrozygous, homozygous. i will be happy if you explain this to me thank you

January 5, 2010 at 5:18 am
(16) jake says:

i didnt understand you all. . . .

March 3, 2010 at 9:29 am
(17) Olivia and Kyle says:

you guys are all nerds and having nothing else to do except disagree with a correct defention. Ya man!!!

March 3, 2010 at 9:39 am
(18) Kyle and olivia says:

Wow all of you are nerds and have nothing to do but fight about a correct definition-Olivia. Ya man!!! Do work son!- Kyle

March 14, 2010 at 3:36 pm
(19) nick says:

you can’t say anything kyle you were on here to!

April 1, 2010 at 5:43 pm
(20) Billie Ridgway says:

If a brown patched tabbyfemale Manx is bred to a Lynxpoint male What colors would the kittens be and how many would be born manx?
If you breed a manx to a cat with a tail, is it possible for any Manx to be born?

April 7, 2010 at 10:57 pm
(21) master says:

Adrianne what you say does not make any sense. If the gene is mute it would not talk at all !! Incomplete dominance is like when you mix the same quantity of two colors and as neither color is stronger that the other what you get is a different color pink.

April 7, 2010 at 11:03 pm
(22) master says:

Moreover, you need to make research because she is not a junior or high school student. Let me remember you Adrianne that you are arguing with somebody that had several years study biology and writing book about science.

April 14, 2010 at 1:03 am
(23) BJBerry says:

So the difference between Co-Dominance and incomplete dominance is that Co- dom is the expression of both allels. Incomplete is the expression of one intermediate trait.

June 28, 2010 at 3:02 pm
(24) SWEnSRQ says:

Actually, Adrianne is correct. Although the original definition gets the right idea across, it does technically define co-dominance. Adrianne is a sharp student.

The “combined” phenotype is, indeed, codominance. Blood types are an example. If you have two alleles for type A, you have type A. If you have two alleles for type B, you have type B. But if you have one of each, you have type AB. If you have type O, you didn’t get either.

Incomplete dominance is when expression of the dominant trait is influenced (“muted” is a good word) by the presence of another allele — in this case, white.

How do I know this? I’ve been teaching biology for 22 years.

August 6, 2010 at 11:11 am
(25) j123 says:

wait, i though codominance was when both genes are expressed fully…like blood type. and incomplete dominance was when neither gene is expressed fully…

September 8, 2010 at 1:27 pm
(26) BRT21 says:

j123 is correct and SWEnRQ provided an excellent example. However, a better way to look at it is to use flowers as an example. Take a pure breeding red flower and a pure breeding white flower and cross them. The results will be as follows:
A) If the red is dominant to the white, the resulting F1s are all red.
B) If the red is co-dominant with the white, the resulting F1s are all red and white spotted.
C) If the red and white display incomplete dominance, the resulting F1s are a shade of the combination of the two. (aka pink)

Hope this helped!

October 3, 2010 at 6:10 pm
(27) jds500 says:

my,my,my… what a lot of controversy… I have to admit, BRT21, what you say makes sense

October 3, 2010 at 9:59 pm
(28) Romel says:

The above definition is correct. It is partially expressed.

December 20, 2010 at 5:19 pm
(29) spiderguy219 says:

what is above is ttttttttttttttttrrrrrrrrrrrrrrrrrrrrrrrruuuuuuuuuuuuuueeeeeeeeeeee!!!!!!!! I have my textbook right in front of my face and it says what Regina Bailey says!!!!!!!!!! Listen to her!!!!!!!!!!!!!!

March 11, 2011 at 8:38 am
(30) tusk says:

thank you SWEnSRQ it makes a lot of sense.

October 15, 2011 at 3:09 am
(31) syed says:


January 3, 2012 at 6:37 pm
(32) josh says:

incomlete dominance – traits mixed
codominance -both traits show

February 3, 2012 at 11:17 am
(33) in-bioliogy-clas101 says:

great definition!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!1 it really helped me understand it. you are a very smart person. WHY ARE YOU SO SMART? I wish i was as smart as you…..

February 3, 2012 at 11:20 am
(34) im-in-biology-class-too says:

i bet im smarter than all of you.. lol jk

February 7, 2012 at 6:38 am
(35) anonymous says:

I came here 2 know the answer 4 my assignment….I thought this is really the answer….but now with all those comments……im stucked….which is really correct the definition above or adrianne’s answer???/

February 21, 2012 at 5:45 am
(36) kim says:

what ever…..

February 22, 2012 at 6:57 am
(37) Confuse16 says:

Now I’m confused I don’t know whether the definition above is really true or not… lemme tell you something Adrianne is the one who caused all the people to argue about the meaning of Incomplete Dominance….

February 22, 2012 at 1:58 pm
(38) Mila says:

Adrianne you are wrong, if it were co-dominance, the colour of the flower would be red AND white not a mixture of the two, (pink)

March 5, 2012 at 4:39 pm
(39) Logan says:

Your both right, red hair is a mutated gene and yes it does appear quite often. Master stop being annoying, it is in a way muted and yes both genes are emitting qualities. Both Andrianna and master are right just worded differently.

March 7, 2012 at 7:54 am
(40) NJ Labuca says:

what is written above is right ; however co-dominance and incomplete dominance is closely relative to the point, but what differs is that incomplete dominance is INCOMPLETE( from the word itself) while in co-dominance both alleles contribute in the changes of the phenotypes :)

March 7, 2012 at 5:15 pm
(41) katie says:

wow yall are smart

March 15, 2012 at 10:28 pm
(42) bus says:

great definition brother!!

March 21, 2012 at 10:15 pm
(43) Alice says:

Incomplete dominance is when the alleles blend, resulting in a mix of the two phenotypes. An example is snapdragon flowers. Pink snapdragon flowers are produced from a white-red cross.

Codominance happens when an organism shows both of the parent’s phenotypes at the same time. A black cat and a tan cat reproducing creates a tabby cat. The tabby cat displays the phenotype of the black cat (stripes) and the tan cat at the same time.

April 26, 2012 at 10:41 am
(44) Michaela says:

ummmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm wow.

May 23, 2012 at 2:56 pm
(45) Adrianne Beaver says:

HEY!!!! We have the same name LOL

May 28, 2012 at 2:59 am
(46) gray says:

@Adrianne has a point. i think the definition bailey stated is co-dominance.

May 28, 2012 at 3:03 am
(47) gray says:

@Adrianne is right. i think the definition bailey stated is co-dominance.

June 7, 2012 at 7:36 am
(48) Kaylee says:

WOW if you have computer access why dont you just go onto wikipidea or something and look up the answer.

September 12, 2012 at 11:59 am
(49) Raunak says:

Does Incomplete Dominance Nulifies Or Justifies Mendel’s Law?

November 17, 2012 at 4:15 pm
(50) wendy says:

Some of these answers are correct, some are partially correct, This link clears up the issue and very simply explains the difference between incomplete dominance and co-dominance. There is also a good example of a Punnit Square and how one works,


November 20, 2012 at 2:39 pm
(51) Arnold says:

I think I speak for all of us when I say “Hey Arnold”

December 1, 2012 at 1:13 am
(52) misschalktalk says:


Incomplete dominance will produce a third phenotype which contains the “blending” of the parental traits (Yellow + Blue = GREEN)

Codominance on the other hand, will also produce a unique phenotype in which both the parental traits will “appear together” (Red + White = Spotted red and white)

biology is fun :)

December 4, 2012 at 5:13 pm
(53) Tool says:

Adrianne is right

December 10, 2012 at 10:49 pm
(54) adeel zafar says:

adraine you r wrong. the definition provided by bailey is correct. stay blessed.

January 31, 2013 at 10:42 pm
(55) lol says:

well i tjink that is a dominant thing lmao idk what were tllking abt lol peace out 😝

February 1, 2013 at 1:53 pm
(56) Deanna says:

The definition above is correct. Codominance is when BOTH alleles are expressed in the hybrid.

February 24, 2013 at 3:44 pm
(57) Bob says:

Cool and Hi :) :) :D : P :q

March 5, 2013 at 8:57 pm
(58) carly says:

thank u so much 4 the message…. :D

May 3, 2013 at 11:14 am
(59) Rashel says:

lol@ you little kids

December 12, 2013 at 8:27 pm
(60) lolly01 says:

bio in 8th

December 12, 2013 at 8:32 pm
(61) greg says:

bio in 8th grade rules

January 20, 2014 at 4:26 pm
(62) Michael says:

This is my homework

January 23, 2014 at 12:07 am
(63) moko says:

What she says is incorrect! Well, to be specific, the very first sentence is true and in fact correct but evey thing after is incorrect. That maybe the reason why so many people are arguing and confused. Part is wrong and part is right. Please focus on the terms more carefully. She techically defined codominance. I have my textbook right in front of me too people and memory, and I checked other websites just to be sure.

Incomplete dominance- has gene for both alleles but only expresses one.
Ex: R-red color petals r-white colored petals.

Example 1(Incomplete dominance): Genotype: Rr and only expresses the red color. Therefore red is dominant but the white is still a part of the gene, just “muted”.

Example 2 (Codominance): Genotype: Rr and color of petals is pink. Red and white traits are physically expresses at the same time (the phenotype) hence the “Co” part in codominance)

January 23, 2014 at 12:20 am
(64) Moko says:

Sorry scratch that last comment guys I accidently mixed the text form my friend in there. Heres the definirion for both.
Codominant: pattern where the phenotypes of both homozygous (same trait) parents are produced in the heteroozygous (different trait) offspring so that both alleles are equally expressed. Lile spotted flowers or orchids. Something like that.

Incomplete dominance: inheritance pattern wheee the phenotype of a heteroozygous is intermediate between those of the two homozygous; neither allele of the pair is dominant but combine and display a new trait.

February 5, 2014 at 5:23 pm
(65) andrew says:

all of you are wrong its when you have three traits being mixed onto a punnet square………….and im only in seventh grade

February 19, 2014 at 9:10 pm
(66) Sharkiesha says:

Andrew honey your in 7th grade for a reason to learn, Don’t play with the Big Kids information.

February 27, 2014 at 4:23 pm
(67) Something says:

Haha lol im 6 years ahead of all of these comments lol

May 20, 2014 at 9:26 pm
(68) shadow says:

Good website to use! :) LOL ^5!

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