Question: how old are the ncis characters?
Answer: Gibbs: 62 (as seen on his ID in 15x01 he was born November 21, 1954)
McGee: 39 (as mentioned by him in 15x01 he was born September 13, 1978)
Abby: 39-41 (I can't say for sure but it appears that she is about McGee's age)
Bishop: About 35.
Torres: About 37.
Ducky: Late 70s.
Palmer: Early 40s.