Authentic persons do not have to prove anything to others. They are themselves in every situation. When asked for their opinion, they will give an honest answer, even if their opinion is not popular. They do not find themselves in an environment where lying or lack of honesty often occurs.
People who value authenticity generally have no problems with self-acceptance. They can easily see falsehood or insincerity in the behavior of others.
Not all people want to be confronted with the truth. Sometimes it can be uncomfortable or painful for them. It is worth knowing how to be tactful.