Generally speaking, moles do not grow overnight, but are formed after long-term development and are only found occasionally. There are many reasons for growing moles, including genetic factors, genetic defects, abnormal hormone levels, local friction and so on. 1. Genetic factors: Some patients grow moles because they are affected by genetic factors, such as abnormal cell differentiation of melanocytes in the process of development, which leads to a large number of pigment cells gathering and forming moles. 2. Genetic defects: Genetic defects caused by various reasons can affect the development of melanocytes in the body, thus leading to melanin deposition and the phenomenon of growing moles. 3. Hormone level abnormality: when the estrogen and progesterone levels in the patient’s body are abnormally high, it can produce abnormality to the melanocyte’s ability to synthesize melanin and the skin’s ability to metabolize the melanocyte, which will lead to melanin deposition in the skin and induce the appearance of nevus. 4. Local friction: In addition, the stimulation of local skin by friction for a long time can also lead to the enhancement of melanin synthesis function of melanocytes, which will lead to the formation of nevus after local deposition of melanin. Once nevus appears on the skin and other abnormal phenomena appear, it is necessary to pay attention to go to the hospital for medical treatment in time.