Although the discovery of mirror neurons has been probably one of the main reasons why empathy is so widely discussed today, the role of mirror neurons in empathy is much less clear than our folk knowledge established around it.
Even more, the claim that we are hard-wired for empathy because of the automatic activation of our mirror neurons is not correct.
Mirror neurons and their role in empathy
Mirror neurons are a type of brain cell which respond equally when we perform an action and when we witness someone else perform the same action. A lot of research has been done and is ongoing on the role of the mirror neurons in empathy.
Research has for instance shown that when people watch facial expressions of well known emotions (i.e. anger, sadness, happiness etcetera), they themselves activate the facial muscles involved in these emotions. Areas associated with mirror neurons are activated in the brain when doing so. This made mirror neurons likely candidates to be the building blocks and precondition for empathy.