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C codominance
Codominance is characterized by distinct expression of the gene products of both alleles in heterozygous conditions.
Both the alleles in AB blood group express themselves and their gene products (antigen A and B) are phenotypically detected.
Complete dominance means that both in the homozygous and heterozygous conditions, the dominant allele expresses itself.
Incomplete dominance means the heterozygous individual will have an intermediate phenotype, between the two contrasting homozygous phenotypes. This is because one copy of the gene is insufficient for expression, thus leading to expression of both the allels which results in an intermediate phenotype.
Mixed inheritance is also known as blending inheritance; according to this, an offspring inherits characters which are the average of its parents. This is different from incomplete dominance because in incomplete dominance, the self-fertilization of intermediate phenotypes produces the parental characters, which disqualifies the blending nature of genes.