What we mean when we say that something is "cultural" is that it is roughly similar to what we find in other members of the particular group we are considering, and unlike what we would find in members of a contrast group. This is why it is confusing to say that people share a culture, as if culture were common property. We may have strictly identical amounts of money in our respective wallets without sharing any of it!
Pascal Boyer, Religion Explained: The Evolutionary Origins of Religious Thought
anthropology, culture