I always find my horoscope to be eerily accurate. As a taurus I hold all the traditional traits. Stubborness, a love of expensive and luxurious things, a need to be part of nature and I'm drawn to romance. My brother is the poster boy for Gemini, and my mom is Leo down to the 't'.
As for the history of the zodiac and horoscopes, it's based a lot off of Greek mythology (ie, Virgo is actually the Greek goddess Demetre, and her traits are based off of the mythology surrounding her.) I don't know how they corispond to the months of the year, but mythology would state that during certian months different planets align and those would influence your personality. I don't know the entire history, and if I did I wouldn't bore you with the details, but it's very spiritually oriented with the ideas that planets and gods dictate our fates and personalities. Its like the idea that if you add up all the numbers in your date of birth (Dec 12 1990 would be 1+2+1+2+1+9+9+0) you get a number that corisponds with a card in the Major Arcane of the Tarot Deck and is supposed to give you a look into your personality and your future.
Really it comes right down to whether or not you believe that your life is dictated by some higher spiritual power and can be read through varying forms of divination. one thing I do know is that people do like to say 'this aspect of my zodiac sign applies to me, while this one is completely wrong.' So as Nat put it, it might just be us picking and chosing what we want to believe in what someone else says about us.
And DaWacko, is that enough post content 0_~