That is quite apart from the mannerisms, the social preferences, the food, and of course the language. I frankly admit that I'm not sure what an Australian is, apart from the strictly legalistic business of holding a passport. At home in Australia I know what I can get away with, where I can cut corners. For people who haven't thought about it a lot, there is an automatic assumption that their race and culture are finished products, precious, fixed and eternal. How wrong they are.
Genetic homogeneity is a myth anywhere on the planet earth.
Both Korea and Japan illustrate this clearly. Evidence of Paleolithic settlement has been found in both territories, meaning that humans have been in the area for at least 30,000 years, but an endless cavalcade of ethnic types have left their calling cards since. Korean ethnic origins Korea seems to have been settled by successive human waves. Then there were various kinds of Mongols, Manchus, Jurchens, and so on. At different times there seems to have been some settlement from across the Bohai Sea, that is, from China's Shantung Peninsula.