Trait (The Sims 4)

Trait is a personality system in The Sims 4, similar to the trait system in The Sims 3. The personality system as a building block of Sims in The Sims 4 is a combination of trait from The Sims 3 and aspiration from The Sims 2. There are three kinds of traits in the game: normal traits, bonus traits, and reward traits. Each kind has different ways to earn them.

Learning traits
As Sims socialize with others, they may reveal their traits from certain interactions. For example, asking a Sim's career will reveal if they have the Ambitious trait, or flirting with a Sim may reveal the Romantic trait. The Observant reward trait allows a Sim to instantly learn the traits of other Sims.

List of Traits
Adult sims created in Create a Sim may have up to three traits, and a bonus trait relating to their chosen aspiration. All traits affect a Sim's behavior and emotions, for example, a Creative sim may randomly become Inspired, while a Sim that Loves Outdoors will sink into a low mood if they stay inside too long.

Unlike The Sims 3, there is no soft limit on the amount of traits an individual Sim can have. Further traits can be earned by either completing aspirations and receiving reward traits, purchasing traits with Satisfaction Points, achieving a high level in the Doctor career, and even dying.

The following lists all traits that appear in the game.

Bonus Traits
Each Sim receives a bonus trait upon choosing their initial aspiration that will aid them in fulfilling its goals. Bonus traits are retained even if the Sim's aspiration is later changed.

Toddler Traits
Toddlers can only have one of the following traits. Regular traits can be selected once the Toddler Sim ages up to a Child.

Death Traits
Sims will receive a unique trait upon death that describes the manner of their passing and the abilities they have as a ghost.

Aspiration Reward Traits
Sims will receive a unique reward trait when fulfilling aspirations. There is no limit on the number of aspirations that can be completed, and thus no limit on the number of aspiration reward traits that can be earned.

Child Aspiration Reward Traits
These traits can only be earned when the Sim is a child and completes a child aspiration.

Satisfaction Reward Traits
Certain traits can be purchased with Satisfaction Points. Unlike regular traits, these traits are of narrow focus and usually only grant a single ability.

Hidden Traits
The Sims 4 features numerous hidden traits that are never visible. Many of them are used only for technical purposes, such as marking which secret lots have been visited, or to provide functionality for NPCs. Some hidden traits function similarly to regular traits, but are simply not visible.

Other hidden traits like Left-handed and Right-handed can be set in debug mode or by using cheat codes.

There are also traits that seem to not have any way to acquire through gameplay, where at this point a command input is necessary to obtain:

The following are listed as reward traits but do not appear in the aspiration rewards store:

Sincere - Sincere Sims have more success with Apologies and Compliments.

Memorable - Relationships decay more slowly.