How do phenotypes appear in codominance?
A condition in which both alleles of a gene pair in a heterozygote are fully expressed, with neither one being dominant or recessive to the other.
One of the best examples to show codominance is by explaining blood types.
Our blood types include A,B, AB and O. At this time we will not look at Rh (D) factor.
A can be AA or AO. B can be BB or BO, AB is AB and O is always OO.
The AB type shows codominance as the genotype (AB) is the same as its' phenotype (AB). OO is not codominant as this O is recessive to the other types.