I have a whole lot of knowledge and beliefs. They are firmly ingrained and strongly affect how and what I write (and how I live my life). And sometimes I take a look back and I realize that I have no idea where I got that belief from.
It's funny how our beliefs are like that. One good idea can reach you so strongly that you absorb it wholly. But when you've internalized it, you forget that it was even not part of you.
I don't think it is necessarily a bad thing for your guiding philosophies to be so strong. But when you remember that everything you know is something you were taught or something you discovered, it can be humbling. It may also help you realize how much potential humans have, and much variety we have based just in which ideas we are exposed to and which of those we adopt.