50% of women can see more colors than everyone else

It's a common joke that women are able to see many more shades of colors than men do. Well, it might also be scientifically correct, at least for 50% of women. The key lies in color pigments called iodopsines. There's a iodpsine for red and green that are located in the X chromosome, and a blue one in a non-sexual chromosome. 

However, the X chromosomes can have slightly shifted green and red iodopsines, meaning a woman can carry up to 5 of them, while men only 3. These females, for example, can identify 10 different colors in a rainbow. So now you know, next time you're arguing about shades of colors, it's not that the man is trying to be obtuse. He's physically incapable of telling between the two colors. 

(Source)