Hypersmurf
Moderatarrrrh...
If a human happens to be over 8 feet tall (maybe he has gigantism) he is still a human. (Contrived example I know).
Generally, even if a human is over 8 feet tall (say, an Enlarge spell turning a 6' human into a 9' human) he's still considered a Medium creature.
Under the influence of, say, a Righteous Might spell, he does become a Large creature.
Charm Person description : This charm makes a humanoid of Medium size or smaller regard you as his trusted friend and ally.
If this race is naturally Large - needs a Charm Monster to get him.
-Hyp.