Apart from the reason of heredity, the dark and yellow skins are caused by the abnormal metabolism of the cutin on the epidermis and incomplete cleansing of oil and dirt.

• 黯淡无光、偏晦黄色肌肤，除了遗传原因外，常常是由于表皮的角质层无法正常代谢、油脂、污垢无法彻底清除而导致的。