 Furthermore, while casual dating and premarital sex has become normative in the West, in Asia parents still discourage such practices, where they remain "rare and forbidden".In fact, about 75% of emerging adults in the U.S. and Europe report having had premarital sexual relations by the age of 20, whereas less than 20% in Japan and South Korea reported the same.While emerging adulthood exemplars are found mainly within the middle and upper classes of OECD countries, the stage of development still seems to occur across classes, with the main difference between different ones being length—on average, young people in lower social classes tend to enter adulthood two years before those in upper classes.