I think history is often biased, but that this is more the result of the individual researcher's ideas than of his or her culture. Many historians want to find particular results, because they have an idea in their head and they consider only the evidence that supports their view. They want to prove their own theories and any sorces that suggest it was not as they think, they leave aside as being untrustworthy or false.
I think it is the duty of the historian to describe what the world looked like in earlier times and how people lived. The only objective way to do that is to take all the sources into consideration and based on that make a description of what is most likely to have happened. But this is not always possible, because of the lack of sources or the sources being biased, leading to endless discussion among historians and no more certainty of what happened in the past. This is often frustrating, eg. I'm a history student and most of the times the results of my research are 'it is likely to have been like this, but it could also have been like that, considering the sources you use.' Still the only thing the historian can do is to be as objective as possible, but that is very hard.
'But this I will say to you, Celegorn the fell, by the sight that is given me in this hour, that neither thou nor any son of Fëanor shall regain the Silmarils ever unto world's end. And this that we now seek shall come indeed, but never to your hands. Nay, your oath shall devour you, and deliver into other keeping the bride-price of Lúthien.'