okay lets assume Astrology is real.
The "Soul" may be nothing more than an electromagnetic field powering a complex human machine that's ran by a highly sophisticated "brain" computer. The "Soul" cant be destroyed, just shaped and/or moved from place to place.
The computer of the human machine's base programming (what you do) is decided by the shape of the Soul that's stuck in it. Since this entire universe and all matter in it, from the air you breathe to the chair you're sitting in, is nothing but a bunch of small pieces of matter with weird energies holding it together into different configurations, the shape of the Soul also governs how you interact with everything else. Not how your physical body interacts, mind you. Your Soul.
Everything you learn while you're young and your brain is processing mainly the Theta Waves of the Soul is what really sticks with you. Language, body language, emotive responses, etc. This becomes the stuff run by your subconscious and instinct as you become older. Everything else you learn in life is really just you downloading new stuff or installing and uninstalling programs onto your computer like brain, but we aint talking about that.
The properties (shape) of the "Soul" is shaped primarily by the gravity of celestial bodies. Maybe like the moon, maybe like other planets. Maybe stuff in the Earth itself. The Human Machine's programming (your base personality) is dictated by the shape of the soul that presides in it. The shape of the Soul also dictates the way that the various energy fields of the rest of the universe, as well as the souls and personalities of other human machines.
All Astrology is, is a bunch of people from different cultures looked up in the sky and mapped out where the stars and moon were, cross referenced it with the dates on their calender to see and take notes on the possible shapes of the Soul based on their positions in the sky. And thus their personalities and how they would interact with the world around them.
That is, assuming Astrology were real.
Hell, for all we know, we may just shape our personalities and manifest the things and situations around us because we looked at some astrology descriptions in our younger days and what we read stuck with us.