In South Korea, over 10% of new couples involve a foreign bride. Most come from Southeast Asia (Vietnam, Philippines, Thailand, Cambodia, Indonesia), and others from East Asia (China, Japan). Such couples now produce almost 6% of births. Their children tend to do badly at school and many drop out, the commonly cited reason being the child's poor acquisition of language skills from a foreign mother. In reality, Damunwha ("multicultural children") have no trouble with spoken Korean. Their deficiency is in written Korean, particularly in literary and specialized vocabulary that is largely learned at school. They actually do well in subjects that emphasize the spoken language and social interaction, like music, painting, and physical education. They do badly only in those subjects that require abstraction and memorization, like mathematics and social studies. Damunwha children are also more prone to hyperactivity, impulsivity, and non-compliance with rules. These divergences in cognition and behavior seem confined to children of Southeast Asian mothers, since children of Chinese or Japanese mothers perform as well as those of unmixed Korean parentage. It looks as if the country's social norms, particularly those of Confucianism, favored the spread of certain cognitive and behavioral traits within the Korean population, and more broadly among East Asians. These traits include not only high cognitive ability but also a high capacity to obey rules, to defer gratification, and to control impulsive behavior.