In the world of Harry Potter, it appears that Divination is a mostly hereditary field; the only seers shown in the books are all related. Students studying the field in class, however, appear to have limited luck -- they try to see the future in leaves and cards, but most seem to go nowhere.
Firenze describes the human version of Divination as
Self-flattering nonsense
The centaurs, however, use a form of Divination that is much closer to Astrology. That form, too, appears to have limited success.
Trelawney herself says
Many witches and wizards, talented though they are in the area of loud bangs and smells and sudden disappearings, are yet unable to penetrate the veiled mysteries of the future.
So the question remains: Can a student succeed at Divination via sheer hard work?
