The introvert extrovert thing
Hubby & I just talked about this same stuff last night. I had just gotten home from George Takei's appearance on my campus where I tabled for a coalition I volunteer for. I was telling DH how extroverted Takei seems, and we speculated as to whether the trait was inherent, or whether it was acquired through skill at Star Trek conventions, etc.
Point being, you can develop skills that are no inherent, and develop them to a point where others won't know if they are natural or acquired. Add me to the list of natural introverts who can be extroverted when she has to. It still fails me at times.