What occurs in phenotypic expression?

In the context of genetics, phenotypic expression refers to how an organism's genotype, which is its genetic makeup, translates into observable traits or characteristics. Both dominant and recessive alleles play a role in determining the phenotype.

Dominant alleles are expressed in the phenotype even if only one copy is present in the genotype, while recessive alleles require two copies to influence the phenotype. In cases of incomplete dominance or codominance, both alleles can contribute to the phenotype in various ways, resulting in a physical manifestation that reflects traits from both alleles, rather than just one. This nuance is significant as it highlights the complexity of genetic interactions and the resultant traits that can be expressed.

Therefore, the correct answer emphasizes that the expression of traits can result from the influence of both types of alleles, capturing the multifaceted nature of how genetic traits are displayed in organisms.