I think that there are many ways you can approach this. The most basic would be to define the notion of "culture." What does the idea of "culture" mean? What are the elements that comprise its definition? Defining or explicating the term so that the audience can understand it might help in your explanation. Along these lines, you can work the definition into your own understanding of culture. The idea of a "culture" does not have to be strictly read along the lines of ethnicity or racial composition. One can be part of a youth culture, a political culture, a culture of ideas, and these can converge and interact with one another. It might be interesting to discuss what are some "higher" and "lower" notions in your culture. What is a value in which your culture places a strong and zealous faith? What are the elements that define your culture in terms of values and core beliefs? Opening with this might be interesting. For example, a nice topic sentence to this paper might be to simply put out there, "________ is a value for which my culture would fight to uphold or preserve." That is a very unique way of opening the paper and topic and it would compel the reader to continue examining it. I think that these ways are interesting and unique approaches to the standard writing topic of defining culture.