Oiliness on the forehead may be related to heredity, poor living habits, eating disorders and other factors. 1. Genetic factors: Heredity and other physiological factors may lead to oily brain, and if the parents have oily skin, the probability of their children having oily skin will also increase. 2. Poor living habits: Poor daily habits, such as staying up late, irregular life, skin cleaning is not in place, etc., may lead to oily brain. 3. Dietary disorders: If your daily diet is greasy or you favor foods with high sugar content, such as fatty meats, chocolates, fried chicken, etc., it may lead to more oil on the brain. There are many reasons that lead to oily brain, we suggest going to a regular hospital to check and clarify the cause.