@Evalen Hidden traits are traits only found in NPC sims or sims at a particular level in a job. For example...
Can Apprehend Burglar trait is found in police NPCs or Level 3 law enforcement sims
Can Salute - level 4 military
Immune to Fire - firefighters, bonehilda, genies
Makes No Messes - Maids
Pizza Appreciator - pizza delivery
Pyromaniac - children of firefighters or genies
Asian/Egyptian/French Culture- people from Shang Simla, Al Simhara or Champs le Sims
More can be found here
https://sims.fandom.com/wiki/Hidden_trait
