Sexology is the scientific study of sexual interests, behavior, and function. In modern sexology, researchers apply tools from several academic fields, including biology, medicine, psychology, statistics, epidemiology, sociology, anthropology, and criminology. It studies sexual development and the development of sexual relationships as well as the mechanics of sexual intercourse. It also documents the sexualities of special groups, such as the disabled handicapped, children, and the elderly. Sexologists study sexual dysfunctions, disorders, and variations, such as erectile dysfunction, pedophilia, and sexual orientation. Sexological findings can become controversial when they contradict mainstream, religious, or political beliefs.