If it's green, use the men's room; if red, the ladies' room. ScienceDaily (May 28, 2009) — Our brain is wired to identify gender based on facial cues and coloring, according to a new study published in the Journal of Vision. Psychology Professor Frédéric Gosselin and his Université de Montréal team found the luminescence of the eyebrow and mouth region is vital in rapid gender discrimination.
Thus, green replaces the color blue for boys, while the girls can still claim red/pink as their own. Is that why red lipstick looks so great on women?