So your friend is a Subjectivist, someone who believes that values differ from person to person. I think that childhood beliefs are a mix of opinion, having those values installed in us as a child and knowing the truth. For example, when I was a kid, my parents told me that standing around in the cold would give you a cold. But guess what, science proved that standing around in the cold doesn't give you a cold. And philosophy also helped me learn that you should question everything. As Descartes said, "I was struck by the amount of falsehoods I accepted as a child."