You're born an atheist. You become a theist by incessant proselytizing.
Could the same not be said about anything? Arguably, you know nothing but natural instincts when you're born. Does that mean that nothing but those natural instincts are true?
Just because we aren't born with the knowledge of something doesn't mean it's necessarily untrue. I did not know 2+2=4 when I was born, but I'm fairly certain it's true now.