Color blindness is a genetic condition that results in difficulty distinguishing certain colors from others, and sometimes a complete inability to see certain colors the way they would appear to everyone else. Since it is passed along in genes, it is present at birth and is incurable. It is much more common in men than it is in women, and some studies suggest that as many as one in twelve men are color blind.

The reason it is seen primarily in men is because the gene that codes for colorblindness is carried on the X chromosome. Since men only have one X chromosome, if they inherit an X chromosome coded with some kind of colorblindness they will be affected with the disorder. Women need to inherit two affected X chromosomes in order to display the disorder, and it is therefore extremely rare to see women who are color blind. Women with one affected X chromosome have normal vision, but they act as the ‘carriers’ for the trait, passing on the disorder to 50 percent of their male children. A male affected with color blindness will not pass on the disorder to any of his sons, but all of his daughters will be carriers for the trait.