Roger Moore's on The One show on Beeb 1 tonight and demonstrating his awesome independent eyebrow raising abilities.
They have a maxillofacial consultant on who says it's learned in childhood, although only if you have the genetic ability to do it, and some people retain it in adulthood.
So which are you? I can't do it to save my life. I should make this a poll but don't have a clue how to do that either.