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Inside Mark Harmon's sweet bond with lookalike son Sean Harmon

The father-son-duo are collaborating on NCIS: Origins

mark harmon ncis
Megan Bull
TV Writer
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Mark Harmon will return as Leroy Jethro Gibbs, and it's all thanks to his son, Sean. Given the green light on NCIS: Origins – an upcoming prequel following a fledgling Gibbs – it was Sean who first coined the idea. 

Mark Harmon with his wife Pam Dawber, son Sean and mom Eluse© Getty
Mark Harmon with his mom Elise Knox, wife Pam Dawber and son, Sean

After approaching CBS Studios with the help of his father, Sean and NCIS legend Mark confirmed that they'd secured a slot for the 2024-25 broadcast season this month. Gearing up to reprise his iconic role, Mark will narrate the series, which is set in 1991, embracing the same winning formula as Young Sheldon. Meanwhile, Sean will continue to collaborate with his famous father as an executive producer. 

An unstoppable duo, Mark and Sean have worked together on several projects before, and after teaming up on NCIS: Origins, they're clearly closer than ever. We're taking a look at their unbreakable bond…

WATCH: Meet the real-life partners of the cast of NCIS

A doting father-of-two, Mark shares his sons, Sean, 35, and Ty, 32, with his wife, and fellow actor, Pam Dawber. A low-key family, the Harmon boys have a similar temperament to their parents. 

Asked about their extremely private lives, Mark told TV Insider: "It's not even a choice. It's who we are. We stay home. A lot. I'm not a Twitter guy or a Facebook guy. Our sons aren't into that either." 

Pam Dawber and son Sean Harmon participate in the  Mark Harmon star ceremony on the Hollywood Walk of Fame on October 1, 2012 in Hollywood, California© Getty
Pam Dawber and Sean Harmon in 2012

While Mark tends to avoid questions about his family, he was happy to speak about Sean's 2008 NCIS debut. 

Appearing as a young Gibbs in seven episodes of the show, Sean made his most recent cameo in the 2020 episode 'Everything Starts Somewhere', which chronicles how Gibbs and David McCallum's Donald "Ducky" Mallard became involved in their first case together.

"I'm proud of him taking his work seriously and how he approaches being an actor — not just on this show, [but] just what he has chosen to try to do in his life's work," explained Mark.

mark harmon sean
Sean Harmon as young Gibbs in NCIS

Asked about Sean's cameo in a 2023 interview, Mark echoed this sentiment. "Separate from anything as an actor, you hopefully take pride in who people are individually away from any camera just as people, as citizens," he said. 

MORE: Michael Weatherly's life and career: From NCIS stardom to Mark Harmon feud and lawsuit drama

READ: NCIS star Brian Dietzen sparks major fan reaction with new season 21 photo

"And both our boys have done well and hopefully made smart choices and are doing well daily. Day by day, we have a lot of reasons to be proud of both of them." 

ncis sean harmon
Mark has spoken about how proud he is of his sons

For Sean, the opportunity to play a young Gibbs left a lasting impression, and it's what gave him the idea for a new spin-off series. "The character of Gibbs has been an important part of my life for 20 years, both in watching my father craft the role and previously having the honor to play young Gibbs myself," he said. 

"I always felt there was a tale worth telling about his earlier years, so I am thrilled to be stepping into a producing role alongside [NCIS writers-producers] Gina [Lucita Monreal], David [J. North] and my dad as we tell this story and reveal a new side of this beloved character."