Do the qualities associated with a certain Sun Sign mean people born under that sign are fated to those personality traits?

Yes and no. Astrology and free will are quite compatible. You are your sign(s), but you do have control over your tendencies. Think of it as a guide to your personality. For example, there are positive and negative qualities to all the signs. People tend to blame their Sun Signs for a lot, but you can change those traits if you want to. The negative qualities are simply the challenges we face in our personality, and what we can learn from them. So, yes, you will have a tendency to exhibit that negative quality, but by recognizing it you can change that. You may always have the impulse to express it, but you have a choice about your actions. It's also interesting to note that in astrology, once you’ve overcome a challenge it is better than a positive aspect. The positive qualities of our sign(s) are what we like about ourselves and almost take for granted. That's why astrology is such a powerful guide. Once we understand ourselves, we can work to leverage the good as well as understand and master the not so good.