Most of us have a tendency of copying gestures of our friends and people around us subconsciously.This type of behavior is called mirroring.
Some set of people say that we synchronize our reactions in order to survive and evolve because this makes a person stronger and they are respected in the society.
The other set of people say that this happens because of a neuron which is responsible for recognizing faces and understanding their expressions.


Do you have a habit of copying other's gestures? What's the actual reason for people to act like this?