Body & HealthFact
Roughly one man in twelve mixes up red and green.
Red-green colour blindness affects about 8 percent of men and around 0.5 percent of women of Northern European descent. The reason: the opsin genes OPN1LW and OPN1MW sit on the X chromosome. Men have one X, women two – and need the variant on both for it to show.
Useful: That's why good charts never rely on colour alone, but also on shape or pattern.
Source: en.wikipedia.org