Sims modeled after someone get the suitable traits.
Sims born in game mostly get their traits randomized with each birthday growing up (although I do cheat sometimes if I think a trait doesn´t "fit" the sim). This way I end up with sims that are grumpy and irresistable, which is hilarious to watch.
I only learned very late that some traits are considered "good" or "bad". I don´t really get that concept - grumpy sims have the most adorable facial expressions, while friendly sims are a bit of a bore (for me, that is).
The only trait I don´t play anymore is diva. Drives me up the wall.
