Does everyone try to "pass" as something he/she is not knowingly? Some do but not everyone. Some become something else until they get what they want then resort back to who they really are. Or maybe they try to be something else because they are insecure about themselves. Whatever those insecurities may be.
Is it possible to do it unknowingly? I'm no psychiatrist or psychologist but I would imagine so. Have you? No. Whether you like me or not, what you see is what you get. The good, the bad, and the ugly of it.