Color blindness is not actually blindness at all but the inability of a person to perceive one or more colors in the color spectrum. It corresponds to damage to retinal cones in the eye tissue that transmit color information from the eye to the brain for processing. It is a genetic disease and different forms of the disease can be traced to 19 different chromosomes and 56 different genes but in humans it can be most commonly linked to a genetic defect in the X sexual chromosome. This is why color blindness affects men more often than women since men have only one X chromosome and women have two X chromosomes. If women have one defective X chromosome they have another healthy one to compensate whereas men do not have such a backup. The genetic defect is usually present at birth but it can manifest itself at various points in a person's life.