“When researchers asked subjects to determine the socio-economic class of people their faces, subjects were correct 68 percent of times. This figure is considerably higher than predictions made randomly.”
[…]
“Though subjects were not aware of how they were determining it correctly, researchers wanted to know. So, they zoomed in to the images to extract facial features. They discovered that subjects were able to guess correctly by noticing eyes and mouth. Mouth gave a clue in better way than others. However, the isolated parts did not guide them to arrive at the decision. Researchers found that this effect could take place due to emotion patterns getting etched into faces over time. The chronic contraction of few muscles could lead to changes in facial structure. These changes can be picked up by others.”
[…]
“Rule told the University of Toronto, “Over time, your face comes to permanently reflect and reveal your experiences. Even when we think we’re not expressing something, relics of those emotions are still there.””