Of course we all have biases, but an historian has to set aside those biases for the time being. History written with bias is propaganda. Most of us decry the trend toward the teaching of history from an ethnic viewpoint, ostensibly for some worthy social or political goal, but that is precisely what propaganda is intended to do. You can't have it both ways. History told with a Southern or Northern bias is not essentially different from black history, feminist history, or counter-western history.
History should be kept clean. The readers of history can and should draw whatever lessons or inspiration they wish, but those who research and write history must strive to stick to the facts.
I am surprised and most disappointed that this is even a topic of debate. I expect better than that from people whose opinions I have come to respect.