Since 1970, sociologists Paula LeMasters and Melvin Kohl have set out repeatedly to research class-based cultures. Class culture has been shown to have a strong influence on the mundane lives of people, affecting everything from the manner in which they raise their children, initiation and maintenance of romantic relationship to the color in which they paint their houses. The strongest cultural differences seem to run along the professional middle class-working class divide. A recent increase in residential class segregation and the overall tendency of individual to associate mostly with those of equal standing as themselves has further strengthened class differences.