What he's saying is that traits are picked up as you play the game (based usually on how you react to conversations).
For example, when you find the dead body of the jumper on the beach at the start of the game, you can either go with a conversational response that will reward you a Romantic trait, or a response that will reward you the Pragmatic trait. Having the Romantic trait boosts your social skill "Lucky Charm" by 1, where as having the Pragmatic trait boosts your social skill "Reason" by 1.
The last time I checked, it was basically a sliding scale with the rewards capped at 1. So, if over the course of several hours of play you made five Romantic conversational choice, and five Pragmatic conversational choices, you would essentially be considered neither Pragmatic nor Romantic, and receive no bonus to either the Reason or Lucky Charm social skills.
If you made 17 Romantic choices and 2 Pragmatic choices, your character would still only be considered a "Romantic", and only have a bonus of 1 in Lucky Charm (not a bonus of 15 as you might expect).
