Is Art Purely Based on Taste and Culture?

Art is a form of expression from the artist, but what determines how he expresses, and what he expresses as art? On the other hand, what do we employ to observe art, to appreciate or criticize, generally relate to art? Art is often argued to be based on taste and culture; they are the factors which influence vital elements of art, from the artist's expression to the critics. However, is art solely based on taste and culture, that the artist's artistic expression and the critics' opinions on art can by no means be affected by other factors?
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