Hidden trait

Hidden traits are in The Sims 3 that cannot be seen in-game except when a Sim performs a related action autonomously or an unlocked interaction is available.

Hidden traits become available to Sims in specific careers, life states, or the children of a Sim with the hidden trait. There's a 50% chance the child might inherit the hidden trait.

Burglar

The Burglar hidden trait can be found in burglars and Sims working in the Criminal career^{[confirmation needed]}.
Burglars must perfect their sneaking skills to properly liberate imprisoned items from the homes of neighbors. Burglars like to keep the skill in the family, so their children are able to sneak out like a pro at birth.

Abilities

• Can "Sneak" instead of walking or running.

Can Apprehend Burglar

The Can Apprehend Burglar hidden trait can be found in police officers and Sims working in the Law Enforcement career^{[confirmation needed]}.
Police officers spend years learning how to best the most clever burglars. Luckily for their children, genetics helps them stop burglars without years of tedious training.

Abilities

• Can fight any burglars on home lot.

Can Salute

The Can Salute hidden trait can be found in Sims who reach level 4 of the Military career. Sims who graduated from Fort Starch Military School also receive this trait. Children who reach level 2 of Scouting also gain the ability to salute.
Children of high-ranking military officials know enough about the military's rules and regulations to snap off a smart salute when they want.

Abilities

• Can "Salute" other Sims.

Immune to Fire

The Immune to Fire hidden trait can be found in firefighters, Sims working in the Firefighter profession, Bonehilda, and Genies.
Fire Fighters are able to survive countless fires; not least because of their natural immunity to fire. It's a trait that they pass on to their children.

Abilities

• A Sim cannot be killed by fire, but they can still be singed.

Makes No Messes

The Makes No Messes hidden trait can be found in maids and resort maintenance workers.
The descendants of maids have cleanliness imprinted on their genetic code so they never leave anything dirty.

Abilities

• Never causes messes, similar to an attribute of the Neat trait.

Pizza Appreciator

The Pizza Appreciator hidden trait can be found in pizza deliverers.
Pizza delivery folks develop a love of pizza that's deeper than the thickest crust. Their children share a similar fanaticism for pizza, which makes every bite of hot pizza amazing.

Abilities

• Eating pizza grants a Sim the Amazing Meal moodlet.

Pyromaniac

The Pyromaniac hidden trait can be found in children of firefighter.
You can only get this trait in a Sim who is the offspring of a firefighter Sim. The trait allows them to set fire to objects of their choice, and they get positive moodlets for doing so!

Abilities

• Can transmogrify any fruit and turn it into a flame fruit.
• Can set things on fire for a short time without destroying anything.
• A Sim with the Pyromaniac trait can survive until three hours when on fire, instead of the regular one hour. Thus their moodlet will be positive.
• If a Sim in a house has already bought the Fireproof Homestead lifetime reward, a Pyromaniac Sim will not be able to set a fire on that house.
• Despite the fact that the fire does not harm anything, it will still trigger the fire alarms if there are any nearby, summoning the firefighter and leading to a fine.

Rocker

The Rocker hidden trait can be found in children of Sims in the Music career.
Sims with this trait will get a natural feeling of rock stardom.

Asian Culture

The Asian Culture hidden trait can be found in Sims from Shang Simla.

Abilities

• Chinese-themed idle animations are triggered on Sims.
• The Sim uses chopsticks when eating.
• The Sim sings Chinese songs autonomously.
• The Sim bows when greeting other Sims.

Egyptian Culture

The Egyptian Culture hidden trait can be found in Sims from Al Simhara.

Abilities

• Sings Middle Eastern songs autonomously.
• Egyptian-themed idle animations.

French Culture

The French Culture hidden trait can be found in Sims from Champs Les Sims

Abilities

• The Sim greets other Sims with a dual-cheek kiss (known in real-life France as La bise.)
• The Sim sings French songs autonomously.
• The Sim gets a discount when visiting France.

Mummy

The Mummy hidden trait can be found in Sims who are mummies.

Private Eye

The Private Eye trait is a hidden trait added with Ambitions. It is gained by reaching level 7 in the Investigator profession. This trait has no icon.

Abilities

• Sims have the ability to sneak.
• A Sim can bribe or beat up to convince another Sim while completing an opportunity, even if they don't work in the Investigator profession anymore.
• This hidden trait is passed on to their children.

SimBot

The SimBot hidden trait can be found in Sims who are SimBots.

Vampire

The Vampire hidden trait can be found in Sims who are vampires. Any child of a vampire (one or both parents are vampires) will receive the vampire trait but will not show any vampire signs until they come of age.

Abilities

• Makes Sim behave like a Vampire.
• Sims with this trait can "Show Off Teeth".
• Vampires snore V's instead of Z's.

Imaginary Friend

The Imaginary Friend hidden trait can be found in Imaginary Friends or in any Sim who was once an Imaginary Friend. It has no icon.

Unicorn

The Unicorn hidden trait can be found in Unicorns. It has no game icon.

Genie

The Genie hidden trait can be found in Sims who are Genies. It has no game icon.

Wished for World Peace

The Wished for World Peace hidden trait can be found in Sims who have wished for World peace from a Genie. This trait may be passed on to the Sims'children. It has no game icon.

Abilities

• Sim can talk about "World Peace" with another Sim.

Wished for World Misery

The Wished for World Misery hidden trait can be found in Sims who have the Evil trait and wished for World Misery from a Genie. The trait may be passed on to the Sims' children. It has no game icon.

Abilities

• Sim can talk about "World Misery" with another Sim.

Wished for Long Life

The Wished for Long Life hidden trait can be found in Sims who have wished for long life from a Genie. Sims with this trait will have their age doubled on every life stage. The trait may be passed on to the Sims' children. It has no icon.

Wished for Beauty

The Wished for Beauty hidden trait can be found in Sims who have wished for beauty from a Genie. The trait may be passed on to the Sims' children. It has no icon.

Wished for Large Family

The Wished for Large Family hidden trait can be found in Sims who have wished for large family from a Genie. Sims with this trait will receive "Feeling Fertile" moodlet that results in birth of triplets if the Sim tries for baby. This trait is apparently temporary and goes away after the Sim tries for baby^{[confirmation needed]}. It has no icon.

Wished for Happiness

The Wished for Happiness hidden trait can be found in Sims who have wished for happiness from a Genie. Sims with this trait will get the "Eternal Joy" moodlet indefinitely. The trait may be passed on to the Sims' children. It has no icon.

Ghost

The Ghost hidden trait is found in ghosts after installing the Supernatural expansion pack. It has no game icon. 

Spellcasting

The Spellcasting hidden trait is found in witches.

Abilities

• Unlocks the magical interactions. However, this trait alone is not enough to unlock the Spell, Curse, or Charm interactions. The trait does unlock these interactions no matter what life state (if using a mod) the Sim is in.
  1. Conjure Apple (or Poisoned Apple if the Sim has Evil trait).
  2. Unlocks "Whiz on Magic," "Brag about Broom Riding," and "Enthuse about Magic" interactions.

Lycanthropy Human

The Lycanthropy Human hidden trait is one of two hidden traits found in werewolves. Apparently, this trait appears in Sims in their human form, and it unlocks several interactions, but not werewolf abilities.

Abilities

• Make Sim behave like a Werewolf.
• Sims can "Joke about Shedding" and "Show Off Teeth".
• Sims with this hidden trait cannot ask for the werewolf curse from other werewolves.
• This trait does not enable Sims to transform into werewolf form.

Lycanthropy Werewolf

The Lycanthropy Werewolf hidden trait is one of two hidden traits found in werewolves. This trait is presumed to appear in Sims in their werewolf form. However, this trait does not unlock the abilities that appears on Lycanthropy Human trait.

Abilities

• This trait does not enable Sims to transform into werewolf form.
• Interactions from the other trait are not unlocked. On the other hand, Sims can ask for the werewolf curse even though they possess this trait.

Fairy

The Fairy hidden trait can be found in Sims who are fairies.

PlantSim

The PlantSim hidden trait can be found in Sims who are PlantSims.

Junior Mascot

Junior Mascot is a hidden trait in University Life. It allows Sims with the trait to change into mascot outfits and do mascot dances.

Influence Nerd

Influence Nerd is a hidden trait a Sim receives as they gain influence in Nerd social group. Nerd interactions and activities are still limited to the influence level a Sim has, but having this trait will make Sims more likely to do nerd activities.

Influence Rebel

Influence Rebel is a hidden trait a Sim receives as they gain influence in Rebel social group. Rebel interactions and activities are still limited to the influence level a Sim has, but having this trait will make Sims more likely to do rebel activities.

Influence Jock

Influence Jock is a hidden trait a Sim receives as they gain influence in Jock social group. Jock interactions and activities are still limited to the influence level a Sim has, but having this trait will make Sims more likely to do jock activities.

There and Back Again

There and Back Again is a hidden trait. Sims will possess this trait temporarily while they have the "There and Back Again" moodlet, which is gained by ranting about death from megaphone. Ranting about death while having this moodlet or trait will result death by ranting.

Advanced Art Training

Advanced Art Training is a hidden trait. This trait is earned by completing a series of Advanced Art Training opportunities. The opportunity can only be acquired by Sims who work at the Art Appraiser career at level six, at the abandoned warehouse. Once Sims complete the opportunities, they can paint paintings at any skill level (0 to 9). This is very practical, as Sims normally cannot paint low level paintings if their Painting skill is already high.

Advanced Art Training Brilliant

Advanced Art Training Brilliant is a hidden trait. This trait is earned by completing the Brilliant opportunity, after completing Advanced Art Training opportunities. It allows Sims to willingly create paintings at Brilliant quality.

Advanced Art Training Masterpiece

Advanced Art Training Masterpiece is a hidden trait. This trait is earned by completing the Masterpiece opportunity, after completing Brilliant opportunity. It allows Sims to willingly create paintings at Masterpiece quality.

Mermaid

The Mermaid hidden trait can be found in Sims who are mermaids.

Kraken Cooldown Hidden Trait

Kraken Cooldown Hidden Trait is a hidden trait, apparently given to Sims as a temporary trait after they've encountered the Kraken. It likely stops the Kraken from attacking while the Sim has this trait, to prevent them from being attacked too often in a short time. It may also be related to the Friend of the Kraken Lifetime reward, as there is a cooldown after summoning the Kraken.^{[confirmation needed]}

Future Sim

The Future Sim hidden trait can be found in Plumbots and Sims from Oasis Landing. Sims with this trait are automatically Level 10 in the advanced technology skill. This trait is also found in Sims who have the Future Sim Lifetime Reward. 

Trivia

• If a Sim has the Good trait and the secret Private Eye trait, the Sim won't have the option to beat up other Sims for information.
• The ability to Sneak with the secret Private Eye trait is only available for young adults and older.
• With the secret Can Apprehend Burglar trait, if the Sim has the Coward or Good trait, they are unwilling to fight burglars.
• Even though a Sim has the Immune to Fire hidden trait, they can still be caught on fire from inventing, making metal sculpture, taking an experimental treatment from the Science Career, or from a fire trap. They will get the Singed moodlet, but they won't die if they catch fire again.
• Sims can get the Unicorn trait by using a 3rd party mod.
• There are four more hidden traits which have no effect on Sims. These are labeled "DNT", and come with The Sims 3: Showtime. These hidden traits cannot be obtained unless a third party mod is used.
• Using 3rd party mods or cheats to simply add the hidden traits for various occults does not properly apply occult status and will cause problems.
• The Ghost hidden trait is one that is introduced in Supernatural. Even though ghosts have existed since the base game, the trait is featured in this expansion pack. It's unknown what differs it from ghosts without this trait, or whether existing ghosts are automatically given this trait. It may be related to the haunting curse ghosts.