The relationship between culture and identity is especially important in poetry. Poets often write within traditional genres, either following the traditions, modifying or challenging them, or sometimes combining both responses. Thus, almost by definition, writing poetry -- especially lyric poetry -- involves a complex interaction between culture and identity.
The culture of a country deeply influences how we identify ourselves. Drawing on the example above, the US and Japan have very different ideas about identity and individualism. The US, for example, has the saying "the squeaky wheel gets the grease" meaning that you have to speak up and stand out to get what you need. The Japanese on the other hand have the saying "the nail that sticks out gets hammered" meaning that it is important to fit in and follow along. In the US, people tend to value being an individualism over group identity. Japanese tend to value the group identity over the individual. Many middle-eastern cultures also take the approach of the group or the family over the individual. The history behind these ideals and the cultures themselves influence much of the poetry and other literature that is produced by these groups.
Culture can also have a great impact on how we identify ourselves. Americans, for example, live in a very individualistic culture and identify themselves as individuals. People in other cultures (Japan, for instance) are much more likely to identify themselves with groups such as their family or the company for which they work. In this way, culture impacts what identity we choose to emphasize.
Should this question not be under the topic Social Sciences?
Since cultures emerge from the repeated celebrations, actions, beliefs, and perceptions of a people, they, therefore, represent the identity of this people who form a nation or an ethnic group. The relationship is one that is inextricable. The American College Dictionary defines culture as
the sum total of ways of living built up by a group of human beings, which is tranmitted from one generation to another.
With reference to the Discussion topic of "Poem," poetry certainly includes much of the culture from which a writer comes, and the understanding of a poem is contingent upon the reader's comprehension of the history of thought of that writer's culture.