These include the presence of sexually arousing fantasies, behaviors or urges that involve some kind of sexual activity with a prepubescent child (with the diagnostic criteria for the disorder extending the cut-off point for prepubescence to age 13) for six months or more, or that the subject has acted on these urges or is distressed as a result of having these feelings. The criteria also indicate that the subject should be 16 or older and that the child or children they fantasize about are at least five years younger than them, though ongoing sexual relationships between a 12- to 13-year-old and a late adolescent are advised to be excluded. A diagnosis is further specified by the sex of the children the person is attracted to, if the impulses or acts are limited to incest, and if the attraction is "exclusive" or "nonexclusive".The ICD-10 defines pedophilia as "a sexual preference for children, boys or girls or both, usually of prepubertal or early pubertal age". Like the DSM, this systems criteria require that the person be at least 16 years of age or older before being diagnosed as a pedophile. The person must also have a persistent or predominant sexual preference for prepubescent children at least five years younger than them. The ICD-11 defines pedophilic disorder as a "sustained, focused, and intense pattern of sexual arousal—as manifested by persistent sexual thoughts, fantasies, urges, or behaviours—involving pre-pubertal children."
Pedophilia appears to be less common in incest offenders, especially fathers and step-fathers. According to a U.S. study on 2429 adult male sex offenders who were categorized as "pedophiles", only 7% identified themselves as exclusive; indicating that many or most child sexual abusers may fall into the non-exclusive category.Some pedophiles do not molest children. Little is known about this population because most studies of pedophilia use criminal or clinical samples, which may not be representative of pedophiles in general. Researcher Michael Seto suggests that pedophiles who commit child sexual abuse do so because of other anti-social traits in addition to their sexual attraction. He states that pedophiles who are "reflective, sensitive to the feelings of others, averse to risk, abstain from alcohol or drug use, and endorse attitudes and beliefs supportive of norms and the laws" may be unlikely to abuse children. A 2015 study indicates that pedophiles who molested children are neurologically distinct from non-offending pedophiles. The pedophilic molesters had neurological deficits suggestive of disruptions in inhibitory regions of the brain, while non-offending pedophiles had no such deficits.According to Abel, Mittleman, and Becker (1985) and Ward et al. (1995), there are generally large distinctions between the characteristics of pedophilic and non-pedophilic molesters.