Codominance

All the pea plant characteristics that Mendel studied had dominant and recessive alleles.

Sometimes traits are controlled by codominant alleles that are neither dominant nor recessive. Both alleles are expressed in the offspring. Chicken feather color is an example of codominance.

When homozygous black and homozygous white chickens are crossed, the offspring inherit one allele for each color. Both alleles are expressed, resulting in a black and white feather pattern.

Codominant alleles are symbolized using capital letters with superscripts.