Dominant V. Recessive Phenotype

Genes can be either dominant or recessive. Only one dominant allele is needed to look like that trait while two recessive alleles are needed for a recessive trait to appear or show up. Recessive traits are masked by dominant ones. In science dominant alleles are typically capitalized where recessive alleles are lower cases. In humans a phenotype can be seen with brown eyes and blue eyes, where a brown eye allele is dominant.