-
Higher testosterone
According to research higher testosterone makes a person less likely to smile. This is one reason why women smile more than men.
-
They are powerful
According to studies smiling can be used as a signal of submission in some situations. Those who don’t smile might not belong to the submissive type.
-
They are less sensitive
People who don’t smile often might be less agreeable than those who smile often. Smiling is often used as a method for communication and those who don’t smile often might not be willing to communicate with others.
-
They are not agreeable
People who don’t smile often might be less agreeable than those who smile often. Smiling is often used as a method for communication and those who don’t smile often might not be willing to communicate with others.
-
They are trying to act tough
Some people try not to smile in order to act tough or to seem stronger. Those people might have learned during their upbringing that smiling makes a person weaker. (See How to differentiate between a genuine smile and a non-genuine smile?
-
They are unhappy
People who are not happy with their lives or those who are emotionally burdened might find it very hard to smile or to laugh.
-
It’s a defense mechanism
People who were emotionally hurt in the past or even bullied might choose not to smile in order to protect themselves from further damage. In such a case, not smiling is considered a defense mechanism. (See Why Eminem never smiles?)
-
They don’t look good when they smile
Some people don’t smile often because they think they look bad when they smile. Believing they have bad teeth is one example that could make a person smile less.
-
They want to be taken seriously
Some people might chopse not to smile in order to be taken more seriously. Those people might believe that smiling might not make them seem serious.