Sean Murray (Timothy McGee) is actually the stepson of Donald Bellisario, one of the producers of NCIS. Troian Bellisario, who plays Sarah McGee, is Donald Bellisario's biological daughter. Micheal Bellisario, who played Chip Sterling in Season 3, and is the son of Donald Bellisario was also casted. And lastly, Vivienne Bellisario, who is Donald Bellisario's wife and the mother of Sean Murray, played Gibb's mysterious love interest in Seasons 1 and 2.

Now that's some acting family!