How to stop loosing certain traits?

[Valion]

I've frequently noticed that some of my FM's traits always tend to disappear or go down like for example the Spartan trait it almost frequently goes back to stern which irritates me seeing the plus to management is something very useful. How do you prevent certain traits to go down or even disappear?

[MarcusAureliusAntoninus]

Every trait has different triggers to bring them about, and every trait has different triggers that make them go away. Usually it is something commonsense that would realistically bring about a given change in a person's character.

[Aemilius Paulus]

Those traits you speak of are lost when you move to small city and above. Generally, just about every negative trait, every vice, is picked up from prolonged sitting in a small-large-huge city. So let your generals take excursions.

[Valion]

Actually the FM that got the trait brought down is in Roma, My biggest(actually a Huge city) and most advanced xD