I guess I give them the traits. To me, it feels more like these traits develop as the character develops. I come up with the story idea, the character fleshes it out.
I didn't think of characteriscs before or during character creation. For example, my Orc grumbles to himself all the time while traveling. He walks/runs everywhere as he doesn't trust a horse. He also dislikes rain and the dark and only stays in cities long enough to manage his business and then he's off to the woods. My dark elf thief likes living in Riften and being seen as a contributing member of society. He dresses in fancy clothes and likes to share his wealth with the merchants. He also does not do any dirty work in Riften and he's one of the few characters that has an opinion on the Civil War at all.
None of this was planned. The characters tell me.