The character's age doesn't have to be the same as that of his portrayer. Unless the character's date of birth is confirmed to be the same as that of his portrayer in something like this, we should leave their DOBs empty.
The character's age is not always the same as the actor's age. For example, Robert Downey, Jr. is 47 years old and the MCU version of Tony Stark is 41 years old.
Even that's not sure. In The Incredible Hulk book, Ross says he was 27 when he returned from Vietnam. So, if he left Vietnam when the Vietnam War ended, his age would be 62 in the film.
I'm not saying that. We don't know exactly when Ross returned from Vietnam, so, unless we have some official source for the character's age (like in Stark's case), we should base character's age on the actor's age.