What causes moles?

Some scientists suspect that overexposure to ultraviolet light, including excessive sunlight, may play a role in the formation of acquired moles. However, more research is needed in this area. Genes can also have an influence on a person's moles. Dysplastic nevi or atypical mole syndrome is a hereditary condition which causes the person to have a large quantity of moles (often 100 or more) with some larger than normal or atypical. This often leads to a higher risk of melanoma, a serious skin cancer. A slight majority of melanomas do not form in an existing mole but rather create a new growth on the skin. Nevertheless, those with more dysplastic nevi are at a higher risk of this type of melanoma occurrence. Such persons need to be checked regularly for any changes in their moles and to note any new ones. See the Wikipedia article listed under "related links."