AHC: at least one of emperor of China have blond hair.
1 ) Did any non-Han people who invade China (Xianbei, Shatuo, Tangut, Khitan, Jurchen) have any member with blonde or red hair ? Do we know what colour Genghis Khan hair is ? (there are some source that he is red-haired)
2 ) Did Chinese Emperor harem had any foreigner inside ? Chinese send princess outside, did they also accept princess ? Is any son of foreigner concubine had any chance to become emperor ?
3 ) how recessive is blonde hair genetically ? can it be received through female-line only ?
4 ) how chinese judge appearance of their prince/emperor ? Did any foreign-looking prince have any chance to become emperor ?