The Sims 3/Traits

Traits
Sims can have up to 5 traits. Traits influence how a Sim feels, what they want, and how they behave. Sims gain more traits as they grow from babies to young adults. If a Sim has positive experiences as a baby you will be able to pick the Sim's first 2 traits. If they have negative experiences as a baby they will be assigned negative traits. If the baby Sim has been moderately happy growing into a toddler, the traits will be chosen at random. Sims get along better with Sims who have at least one of the same traits.

Trait List
🇨🇴

Mental
🇨🇴
 * Absent Minded
 * Artistic
 * Bookworm
 * Can't Stand Art
 * Computer Whiz
 * Excitable
 * Genius
 * Green Thumb
 * Handy
 * Insane
 * Natural Cook
 * Neurotic
 * Virtuoso

Physical
🇨🇴
 * Athletic
 * Brave
 * Clumsy
 * Couch Potato
 * Coward
 * Heavy Sleeper
 * Hydrophobic
 * Light Sleeper
 * Grumpy
 * Neat
 * Never Nude
 * Slob
 * Unlucky

Social
🇨🇴
 * Charismatic
 * Commitment Issues
 * Dislikes Children
 * Easily Impressed
 * Flirty
 * Friendly
 * Good Sense of Humour
 * Great Kisser
 * Grumpy
 * Hopeless Romantic
 * Inappropriate
 * Loner
 * Loser
 * Mean Spirited
 * Mooch
 * No Sense of Humour
 * Party Animal
 * Schmoozer
 * Snob
 * Unflirty

Lifestyle
🇨🇴
 * Ambitious
 * Angler
 * Childish
 * Daredevil
 * Evil
 * Family-Oriented
 * Frugal
 * Good
 * Hates the Outdoors
 * Hot Headed
 * Kleptomaniac
 * Loves the Outdoors
 * Over-Emotional
 * Perfectionist
 * Technophobe
 * Vegetarian
 * Workaholic

Traits in Detail

 * There is a hidden skill trait called Pyromaniac. It can be gained only through genetics. It is given sometimes to the children of Firefighters. Pyromaniacs can set objects on fire and get a positive moodlet from it. Pyromaniacs can take a fruit and turn it into a Flame Fruit, which they enjoy eating.