If you believe in Astrology, then you would need more information than just the sun sign to rate compatibility by it. There is a thing done in Astrology called a Natal Chart. The natal chart is basically a picture of the sky at the exact moment you were born and where each planet was in the sky and thus in the signs. The sun sign, the one listed in news papers is just a fragment of the Astrological chart for an individual. Knowing the rest of the story helps you to understand why two people in the same sign can be different. So no matter how compatible or incompatible your Sun Sign is the rest of the planets could change the results.