Have you ever been curious to know if someoneâ??s actually smiling or if theyâ??re faking it? Maybe youâ??ve seen someone smile but had a hunch it wasnâ??t genuine. Your first instinct may be to look to the personâ??s mouth to try and spot a fake, but the truth of the matter is inâ??or more accurately, aroundâ??a personâ??s eyes. Leslie Baehr at Business Insider explains: â??There are two muscle groups involved in smiling. The first pulls up the corners of your lips. Since you can manipulate this muscle voluntarily, it is not a good predictor of a real happy smile. â??The other muscle is involuntary and can only be activated by happiness. It is the obicularis occuli, which causes the outer corners of your eye sockets to squint.â?? In other words, itâ??s not just a hunch you have when you sense a fake smile. Youâ??re reacting to a physiological difference between a knockoff and the real thing.