Codominance
Simplest example isnít from cats: itís human blood groups
There are three alleles that govern which ìmolecular markersî you produce on the surfaces of your red blood cells: IA, IB, and i.
Both IA and IB are dominant to i, so if you have IAIA or IAi blood, you have type A blood; if you have IBIB or IBi blood, you have type B; and if you have ii blood, you have type O.
If you have IAIB genotype, you produce both A and B ìmarkersîóand you have type AB blood.