There is also regionalism in play, though it is not as strong as it used to be, especially amongst younger generations.
In particular, the southeast region (Gyungsangdo - GSD) is the core of the right-wing, and the southwest region (Jeollado - JLD) is the core of the left-wing. I really cringe at using the words "right" and "left" here because South Korean politics doesn't neatly align with what many Westerners would think of when hearing those terms. But for lack of better terminology...
In any case, the earlier presidents (or quasi-dictators) hailed from GSD and overtly favoritized their home provinces in terms of economic development, etc. while leaving JLD less developed. This has led to resentments that reflect in politics that persist to this day.
Some would argue the rivalry goes back even further. Historical texts exist that describe animosity between the GSD and JLD regions back into the Joseon dynasty. Going back even further, the GSD and JLD regions were the rival and enemy kingdoms of Shilla and Baekje respectively, the former which eventually conquered the latter.
It used to be that it was even taboo to marry across GSD-JLD lines, but again, this mainly affects the older generations. Personally - while I am Korean-American, my family comes from GSD. My wife is from JLD. My dad is on the conservative spectrum in terms of Korean politics and I was initially worried what he would think when I introduced my then-girlfriend to my parents for the first time. Thankfully it was a total nothingburger and my now-wife and my parents get along absolutely fine.
I once saw a TV clip where they challenged viewers to tell the difference between per-province election results and the response to Sejong's tax system at the beginnings of the Joseon dynasty -- they both had the same GSD/JLD split.
Unfortunately I can't find it now though; it was very insightful.
In particular, the southeast region (Gyungsangdo - GSD) is the core of the right-wing, and the southwest region (Jeollado - JLD) is the core of the left-wing. I really cringe at using the words "right" and "left" here because South Korean politics doesn't neatly align with what many Westerners would think of when hearing those terms. But for lack of better terminology...
In any case, the earlier presidents (or quasi-dictators) hailed from GSD and overtly favoritized their home provinces in terms of economic development, etc. while leaving JLD less developed. This has led to resentments that reflect in politics that persist to this day.
Some would argue the rivalry goes back even further. Historical texts exist that describe animosity between the GSD and JLD regions back into the Joseon dynasty. Going back even further, the GSD and JLD regions were the rival and enemy kingdoms of Shilla and Baekje respectively, the former which eventually conquered the latter.
It used to be that it was even taboo to marry across GSD-JLD lines, but again, this mainly affects the older generations. Personally - while I am Korean-American, my family comes from GSD. My wife is from JLD. My dad is on the conservative spectrum in terms of Korean politics and I was initially worried what he would think when I introduced my then-girlfriend to my parents for the first time. Thankfully it was a total nothingburger and my now-wife and my parents get along absolutely fine.