Mark Harmon has two sons, Sean Harmon and Ty Christian Harmon.
Sean Harmon was born on April 25, 1988 in Burbank, California, USA. Just like his father, Sean Harmon has featured in NCIS. However, Sean only featured in six episodes as "Gibb's" son. Sean Harmon is also a stunt artist and has stunted/stunt co-ordinated in 15 films. He has featured as an actor in 14 films/TV shows. Sean is also emerging as a well-known director.
Not all of the family is in the limelight
Ty Christian Harmon is an emerging name in the screenwriting department of the entertainment industry. Though born into the star family, his name isn’t famous as like his other family members. However, Ty took his first step in the writing field for the short film called Catholic Schoolgirl Chainsaw Showdown in 2012. Amazingly, that short film was directed by his own older brother, Sean Harmon.