Why Do All Koreans Have the Same Last Names? (Featuring Harvard Ph.D.)

Korea seems to be dominated by 3 names, Kim, Lee, and Park. In fact, it’s estimated there were 10,689,967 individuals with the last name Kim, that's 20.6% of the population or approximately 1 in 5 Koreans.

So how did it get this way? Why do so many people in Korea have the same last name? Are they all just related somehow?

Dr Mark Peterson, Harvard PhD
Professor of Korean Studies