What is authenticity anyway? To me, authenticity has to do with revealing or expressing the undefended facets of yourself. There isn't one authentic you. There are many authentic yous.
Think of yourself like a faceted diamond. When the light hits the diamond in a certain way, some facets sparkle. Turn the diamond in the light and other facets sparkle. All of them are facets of the diamond, just like all of your authentic characters are aspects of you.
Some people think this means that reacting defensively is okay since they think of that as authentic reactions. I view it differently. Our defensive reactions are clearly part of us, but I see them as parts of ourselves that are scared, wounded, and fighting to survive. If we stay with the diamond metaphor, our defenses would be like oil or soap that is crudding up the diamond and not letting it sparkle. It could also be like the flaws in the diamond (called inclusions) that don't refract light in the same way as when they aren't there.
Calling the diamond's flaws 'inclusions' is interesting in light of this metaphor. In order for us to come from what I call our authentic self or selves, we have to admit to our defenses, include them enough to notice them, get to know them, find out where they're coming from, and diminish them by making peace inside ourselves and shifting our nervous system from a survive state to a thrive state.
Consider the idea that you have many facets inside you that are part of you and each facet has different characteristics or attributes. Now imagine that you are in a situation in which you want to influence someone. If you are in the director's seat, you look around at your cast of characters and find those whom you believe will help you influence whoever is in front of you in the way you're hoping.
If you follow this idea out, you will find that you have a huge amount of flexibility and options, all of which can be coming from your authenticity.
Play with it and find out how it works for you.