There is an interesting argument that is thrown to an astrologer many a times by both the believers and the non-believers. Even I have asked the same question to few astrologers thinking I was smart enough to put the astrologer down. Not many could give a convincing reply, until I myself learnt astrology and tried finding the answer to it. Will 2 different people have the same future, if they are born on the same day, at the same time and in the same place?
Before answering to that question, let me put some light on two important aspects
1) interconnected of life
2) and that even astrologers have their own horoscope
Interconnected of life
Your present life is completely based on your past karma. If you dont believe this, then you better dont believe in astrology. Astrology was completely formulated on the basis of how past life influences our present life.
You come in contact with only those people in this life, with whom you have had a past connection. This set of people could either be your friends or your enemies - you will still continue to have a bonding. Hence we like to love few, and love to hate many without any particular reasons. There is a small possibility of escaping this cycle of karmic relationships, if you start becoming non-reacting like few those spineless Corporate bosses, who never respond.
People also tend to carry few karmic habits from the past, which can give instant results in the present life. What you sow though shall you reap, said Jesus Christ, and it is absolute truth.
Here is an interesting example it is said that sound sleep is a blessing for people. But there are people who woke up at the slightest of disturbances. It so happened that one of my friends was complaining about how his friend wakes him up in the morning. He slaps, or kicks or pours water on the face. I immediately told him, your friend should be having problems in sleeping. And he said YES. I had seen the same pattern with my elder sister. I hated the way she woke me up, and even she had the same problem, which my friends friend had.
An astrologer is also born with few unique planetary combinations, which attracts only those people to him with whom he has a karmic connection. Indias number astrologer Bejan Daruwalla would always get clients from the premium segment. And I really doubt if he has done an astrological reading for an auto-rickshaw driver. The same thing is true with Enlightened Souls too Osho Rajneesh had an amazing combination to pull the billionaires as his disciples, while Ramakrishna Paramahansa could only attract people with average fortune.
Predictions for people born on the same day, same time and same place
Astrologers prediction for individuals are NOT just based on the planetary combination, it also depends on the level at which the client is at present. The planetary combination for buying a new house is invariably similar in all the horoscopes. If the client is a poor vegetable vendor, we wont be predicting that he will buy a house in Mumbais Hiranandani Gardens. He probably will buy a house in a chawl. And if the same combination for house is visible for a person working for a MNC, the prediction is made accordingly.
For instance, if 2 people are born on the same day, time and place, but one in a Govt hospital and another in a private one am sure you understand how their life pattern will change based on their present level. Both of them will study, just that one will study in a govt school and another in a Christian convent, both of them will do business, just that one will have a small roadside hotel and another a restaurant, both of them will have their own vehicles, just that one will have a TVS 50 and another will have a Ford Ikon, both will meet up with astrologers, just that one will consult the roadside palmist and another will come to ME :D.