Why Do Koreans Have the Same Last Name?

Quick Summary

• Nearly half of all Koreans share just three last names, Kim, Lee, or Park.
• Korean last name quietly carries centuries of heritage, and clues about ancestors’ status and hometown.

What’s a Korean Last Name Called?

In Korean, a last name (family name or surname) is called “Seong (성)”, which sounds closer to Sung.

If you want to be more specific, especially to avoid confusion with the word for gender (also “Seong”), you can say “Seong-ssi (성씨).”

In Korean names, the last name always comes first.

Just like in Park Jimin (a.k.a. BTS’s Jimin), where Park is the last name and Jimin is the first name.

A Little Secret About Korean Last Name

Here’s some hidden info about Korean last names.

It isn’t just a name. It includes the surname (Seong), origin of clan (Bongwan), and specific family branch or faction (Pa).

So two people with the same last name Kim may not be from the same family at all.

When I meet another person with the same last name, the first thing I’ll ask is “Which Seo are you?” I’ll use “where (eodi)” in Korean to be exact.

I’d say, “I’m Icheon Seo-ssi,” which means, “I’m from the Icheon Seo clan.”

The names may be short, but they hold a lot of heritage. Every Korean knows their family clan (place of origin), which comes with their last name. For example, my last name is Seo, but delving deeper, I’m the 3Xth descendant of Icheon (origin) Seo (surname), Wonsukgong-pa (faction). All written in the family genealogy book that my dad holds onto. No need for 23andMe.

In my book, “A Korean Girl Explains“

Why Are Kim, Lee, and Park So Common?

If you look at the numbers,

• Kim = 21.5% of the population
• Lee = 14.7%
• Park = 8.4%

That’s nearly half of all Koreans sharing just three last names.

There’s even an old joke that goes, “Throw a rock in Seoul and you’ll hit either a Kim, Lee, or Park.”

A Korean proverb, “Searching for Mr. Kim in Seoul” is like finding a needle in a haystack.

So, how did it happen?

We have a few theories.

• Genealogy for sale: Some people bought family records (jokbo) or adopted their owners’ surnames during the slavery period.
• Royal name fever: Many chose prestigious last names like Kim, Lee, or Park to boost their social status.
• Regional surnames: Some Koreans were named after their hometowns, like Jeonju Lee or Gyeongju Kim.
• Last names weren’t meant to be diverse. From the beginning, last names may have been intentionally limited due to naming systems.

How Are Korean Names Structured?

Korean names usually consist of three parts.

1. Family name: always comes first
2. Given name (Ireum): usually two syllables
3. Optional generation name (Dollimja) among the given name: shared among siblings or cousins

Dollimja is where it gets interesting.

Among the two-syllable first names, we sometimes have a shared syllable used across a generation within the same family line. It can come as the first or second syllable.

It’s kind of like a naming pattern that links siblings or cousins of the same generation.

So you might meet a group of siblings or cousins named:

• Ji-min, Ji-seok, Ji-yeon, Ji-hoon, or Ji-hye, sharing “Ji” as their generation name
• Min-woo, Yong-woo, Yun-woo, or Jun-woo, sharing “woo”

When using a shared syllable, the other remaining syllable is uniquely their own.

Like, [Last Name] + [Shared Name] + [Unique Name] becomes a three-letter Korean name.

This naming system is not legally required, but many traditional families like to use the generational marker.

Are All Korean Last Names One-Syllable?

Most Korean last names are single-syllable, like Kim, Lee, or Choi, but we DO have some rare two-syllable last names.

They are either:

• Namkoong
• Hwangbo
• Jegal
• Seonwoo

For example, Korean celebrities with these last names are:

• Namkoong Min (actor)
• Sunwoo Jung-a (musician)

Do Koreans Change Their Last Name When They Get Married?

Nope. Never!

In Korea, last names are not changed after marriage, and it’s actually very hard to change them legally at all.

For example,

• Your dad, mom, and siblings will likely not share the same last name. Korean moms keep their maiden names for life.
• You can change your last name under strict legal conditions, like:
  • A child taking their mom’s last name after a divorce.
  • A stepchild adopting a stepfather’s last name with court approval.
  • Or occasionally, when marrying a foreign spouse and moving abroad.

But generally speaking, my Korean last name equals my lineage. And this never changes.

Is It Rude to Call Someone by Their Last Name in Korea?

Yes, very.

Calling someone by just their last name in Korea is considered impolite, unsophisticated, and sometimes even insulting.

Saying “Kim-ssi (meaning Mr. Kim)” sounds off unless you’re joking or being sarcastic.

The acceptable way to use a last name is by pairing it with a title, like:

• Kim Sunsaeng-nim: Teacher Kim
• Park Gyosoo-nim: Professor Park
• Choi Bujang-nim: Manager Choi

The only people who get away with calling others “Kim ssi-deul” as in “Kims” are usually Korean moms. But only when they’re playfully grumbling about their husband + kids.

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So, why do so many Koreans have the same last name?

Because a Korean last name includes a different clan, origin, and identity.

Even if someone’s called Kim, their full identity could be Gyeongju Kim, Gimhae Kim, or Andong Kim with totally different lineages.