Modernization comprises the shift from a traditional society - with its own identity and unique values -, to a more homogeneous and progressive one; a society that holds values able to be found among other societies, removing the unique factor and giving it a globally identifyable identity.
Since the unique aspect is somewhat lost in modern societies, the cultural values follow suit. This ocurrence is mostly due to the heavy influence of mass media (televisions, radio, internet, etc) among the members of a society. This influence opens the doors to a seemingly endless sort of possibilities before the minds of people who previously relied on their own, short-reached knowledge of the world.
Some individuals would decide to adopt these newly-arrived values, while others would prefer to cling to the old traditions, which creates cultural disparity. The more cultural aspects enter the territory of a single nation, the more scattered these aspects would be once people decide to embrace them.