Curious to know your future?

Astrology is a group of systems, traditions, and beliefs in which knowledge of the relative positions of celestial bodies and related details is held to be useful in understanding, interpreting, and organizing information about personality, human affairs, and other terrestrial matters. ...

I find this quite unbelievable yet fascinating. How can the position of planets tell you about an individual's future?

According to my understanding and some discussions with friends who have been to astrologers on a regular basis, astrologer would ask you your DOB, TOB and POB (Date, time and place of birth in that order). And then they would predict your future. The question that pops up in my mind is - 'There are many people with the same 3 things. Does that mean they will all have alike future?'

Another thing is the matching of horoscopes at the time of marriage. I think whats more important is the nature of the two people involved in the relationship. Then from where does this horoscope thing comes.

What really bothers me is that people tend to change their behaviour according to what they have been told. (Many may not agree with me)

I am a person who is not into all this but listening to what my friends have to tell about this, I really wonder how one attains this power of prediction. I dont know any astrolger closely so guess the question would linger on my mind forever.

Any helper???? :D