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If a genetic trait is recessive, a person needs to inherit two copies of the gene for the trait to be expressed. One allele can be dominant to a second allele, recessive to a third allele, and codominant to a fourth. This will subsequently confuse discussion of the molecular basis of the phenotypic difference. For example, to say that “green peas” dominate “yellow peas” confuses inherited genotypes and expressed phenotypes. However, this can easily lead to confusion in understanding the concept as phenotypic. It is sometimes convenient to talk about the trait corresponding to the dominant allele as the dominant trait and the trait corresponding to the hidden allele as the recessive trait. The key concept is genetic: which of the two alleles present in the heterozygote is expressed, such that the organism is phenotypically identical to one of the two homozygotes. The recessive trait will only be expressed by offspring that have two copies of this allele these offspring will breed true when self-crossed.īy definition, the terms dominant and recessive refer to the genotypic interaction of alleles in producing the phenotype of the heterozygote. The recessive allele will remain “latent,” but will be transmitted to offspring by the same manner in which the dominant allele is transmitted. Rather than both alleles contributing to a phenotype, the dominant allele will be expressed exclusively.

Mendel’s law of dominance states that in a heterozygote, one trait will conceal the presence of another trait for the same characteristic. \( \newcommand\): Recessive traits are only visible if an individual inherits two copies of the recessive allele: The child in the photo expresses albinism, a recessive trait.