Reminds me of a friend's anecdote about people in Scotland in the 60's talking about differences in accents resulting from being from a town 9 miles away.
Reminds me of a friend's anecdote about people in Scotland in the 60's talking about differences in accents resulting from being from a town 9 miles away.
A lot of places in Europe are still like that. "In USA 100 years is a long time, in Europe 100km is a long distance"
In this Reddit story, I think they did things like get him Mandarin lessons, practice various customs, find a Chinese "uncle and aunt" to take him to dim sum and whatever else. Then when signing his son up for college applications, the father noticed the surnames of his kid's birth parents were very typical Korean names. All those good intentions!
I'd expect there to be some small degree of genetic distinctness, but there has always been a history of interbreeding. There's even an old Korean stereotype about rich bewhiskered Chinese merchants who come down to marry a hot young Korean wife.
In short -- Ethnic differences between Han Chinese and Koreans: mainly cultural.