Jon Snow

Great art work but I was just wondering why you, and so many over artist, like to draw Jon Snow with native american look to his face? All if the art of his family shows them as purely European but a good number of fan arts have Jon looking mixed and even olive skinned. Is it because of his mother-or father-possibly being from the south or is this how the fan base visualize him? I'm not trying to offend just something that has puzzled me since I got into the fandom.