We're able to make decisions ba<x>sed on free will rather than instinct. We also have differing life experiences and values. Values instilled within children of a strong Christian household differ greatly from those instilled within children of an atheist household.
Natural personality and life experience
we're all different
Freedom of choice.
Intellect and credulity. Some people are just far too quick to believe things without solid evidence.
Good question but can't pin point one major factor. Definitely given me food for thought,
Background, values, education, ideas, experience, age,,,,,etc.........