Culture is a broad term used to describe the habits and practices of society. Cultures differ because people differ–in looks, tastes, and religion–and when there's a hodgepodge of cultures, they mix to create something novel, i.e. America, which then becomes its own cultural pillar.
As broad as culture is, in say music with its infinite number of genres and subgenres, it can also be limiting. For instance, the three most popular operating systems smartphones run on are iOS, Android, and Microsoft. Given the scarcity of choice, people choose sides, resulting in Apple fans, Google geeks, and Microsoft traditionalists.
But even when there's a variety of choice, a favorite always wins out. Whether it's a preferred operating system, musician, film, or shoe style, some cultures become mainstream. If you copy such trends, you are the benefactor of the wisdom of crowds. If you're an early adopter or renegade, you look for things on the edges which are a plausible reaction to the herd mentality.
Given culture’s categorizations, people always conform to a certain type regardless of how big or small a niche. Culture's resistance to sameness guarantees the durability of uniqueness, and there may be no better modern-day American dissenter than Mark Grief who appears to be against everything.
Read Louis Menand's Cultural Criticism and the Way We Live Now