What is the significance of the term "recessive gene" in color blindness inheritance?

The significance of the term "recessive gene" in the context of color blindness, particularly the most common forms like red-green color blindness, is closely tied to its inheritance pattern, which is often X-linked. This means that the gene responsible for this trait is located on the X chromosome.

Typically, males carry one X and one Y chromosome (XY), while females have two X chromosomes (XX). Because males have only one X chromosome, if they inherit the recessive allele for color blindness from their mother (who could either be a carrier or affected), they will express the trait. On the other hand, for females to express color blindness, they must inherit the recessive allele on both of their X chromosomes.

This discrepancy in the number of X chromosomes explains why color blindness is more prevalent in males than in females. It highlights the concept that a recessive gene does not require two copies to express its trait in males, whereas females can be carriers without showing symptoms if they possess one normal allele.

This understanding also explains how color blindness can appear to skip generations, as unaffected female carriers can pass on the recessive gene to their sons, who may then express the condition. However, because the question is focused on the direct expression frequency of