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The Sims 3: University Walkthrough Additional Trait Slots
The Sims 3: University Additional Trait Slots
Your Sims can unlock 2 more trait slots by excel socially and academically (up to 7 traits total). Social Group Trait is attained by reaching level 8 with the first social group. Repeating these accomplishments gives you an option to replace the trait.
Sims who complete University courses and receive a degree in any major will get an extra Academic Trait. Repeating these accomplishments gives you an option to change the extra trait.