This makes males effectively “hemizygous” for genes on the x chromosome More than one recessive gene on the x chromosome codes for this trait, which is fairly common in males but relatively rare in females (figure below). Females, with their two x chromosomes, have a genetic advantage in this regard.
In humans, the term often refers to traits or disorders influenced by genes on the x chromosome, as it contains many more genes than the smaller y chromosome People with this trait cannot distinguish between the colors red and green
