Incomplete Dominance Calculator

In incomplete dominance, the heterozygote shows a blended intermediate phenotype (e.g., red + white = pink). In codominance, both alleles are fully expressed simultaneously (e.g., red spots + white spots in roan cattle, or AB blood type). The heterozygote in codominance is not intermediate but shows both phenotypes at once.

Incomplete dominance is more common than traditionally taught. Many quantitative traits show partial dominance effects. At the molecular level, it often occurs when one copy of a gene produces less protein than two copies, resulting in an intermediate phenotype. Complete dominance is actually a special case where a single copy provides sufficient protein.