Does it follow the incomplete dominance mode or does it follow something else. So in this particular case, we have a mode of inheritance known as codominance. So these three alleles that make up the Abo blood group trait in humans follow a mode of inheritance we called codominance. Now, what exactly do we mean by codominance? Well, in codominance, neither allele is dominant over the other one. And what that means is in heterozygous individuals, heterozygous individuals will basically express both types of phenotypes.