Great question, I would also add...
Metaphysical reasons like Spirit. That which animates and gives life to me will always resonate and interact with the frequencies of life (things) a little differently than someone else's. Identical twins that go through life together will end up different for this reason.
Also, two people who experience the same thing will react differently based on their BELIEFS about that thing.
When we react to something based on our belief toward something, it creates emotions which are energetic epigenetic switches that turn genes on and off creating actual physical and psychological changes within us.
Just my two cents brother.
Peace 🙂,
Michael
RE: What Constitutes Difference In People Irrespective Of Being Exposed To The Same Things In Life?