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.

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.