From what I observe since the first time I played the sims 3 in 2011, sometime the specific traits assigned to some specific sims tend to be more or less potent or they act according to their trait rather differently to another sims, i remembered i once played Frio household, Jared rarely insult or being mean to his brother eventhough he has mean spirited trait, and Connor's loner trait only ignore his wife but still talk to his children autonomously, while my own created mean spirited sims did insult or pick a fight with his wife a lot.