In "Gu Family Book," Choi Jin Hyuk, who is now 28, played the father of actor Lee Seung Gi, who was 27. But there was magic involved in that plot, so maybe that's not so strange.

But then Choi Jin Hyuk, who now stars in "Emergency Couple," is often told that he looks old for his age.

On a recent episode of "One Night of TV Entertainment," he spoke about the sometimes disconcerting fact.

"If I say that Song Joong Ki and I are friends, people say, 'What?' Truthfully I am developing a complex about that," he said.

While Song Joong Ki, Yoon Si Yoon and Kim Hyun Joong are the same age as Choi Jin Hyukis, people often think that he is much older. But it's not as if he is aging prematurely. At 28 he looks just right for his age.

"When I was 20, I looked 28 or 29, but now I think I still look 28 or 29," he said. "I was told that a face like mine looks gradually younger as I grow older."

Daniel Choi is another actor whose age people often overestimate. In "School 2013" the 28-year-old played a teacher, while the ages of the actors playing his students ranged from 14 to 27. Lee Jong Suk, who played a student, was only three years younger than him.

"We're around the same age," said Daniel Choi at the drama's press conference. "But he's a student and I'm a teacher."

In the comedy "High Kick," Daniel Choi played the uncle of someone who was the same age. He's not sure why it happens and joked that it must be something he eats. The actor will soon play a cunning businessman in "Big Man."

In the band 2PM, Hwang Chansung is the baby or maknae of the group but people often think this singer-actor is older than fellow band member Ok Taecyeon. Chansung, 24, will appear this year in the film "Five Siblings in Deoksu Village." Taecyeon, who can soon be seen in the weekend drama "Wonderful Days," is 25.

It may be that these actors don't really look old for their age but that other popular k-drama actors tend to have baby faces and look young for their age.

For example, Lee Jong Suk convincingly played a teen in both "School 2013" and "I Hear Your Voice." Kwon Yong Sang is 32 but the actor, who appeared in "Queen of Ambition," Vampire Prosecutor 2" and "Fugitive of Joseon" could easily pass for a teen.