Part of the problem about authenticity is that virtues aren't the only things that are habit forming: the more someone behaves in a way that is damaging to self or to others, the more "natural" it will both seem and actually be. Spontaneity, left to itself, can begin by excusing bad behavior and end by congratulating vice.
N.T. Wright, After You Believe: Why Christian Character Matters
habit, judgement, spontaneity, vice, virtue