According the DSM-5, the criteria to diagnose Pedophilia (Pedophilic Disorder) is defined as recurrent experiences of intense sexual arousal, fantasies, sexual urges or behaviors involving sexual activity with a prepubescent child or children, usually under the age of 14. The person has acted on these sexual urges or these sexual urges or fantasies cause the person distress or problems in interpersonal relationships.

In order to be classified with this disorder, the person must be at least 16 years of age and five years older than the child or children for whom he has these feelings that are possibly acted upon.

A person in late adolescence involved in a long term sexual relationship with a 12 or 13-year-old is not included in this category (American Psychiatric Association, 2014).

Different theories exist about what causes pedophilia.

Some experts propose that the causes are neurodevelopmental. Differences in the brain structure of pedophiles have been noted, such as frontocortical differences, decreased gray matter, unilateral and bilateral frontal lobe and temporal lobe and cerebellar changes.

According to research, these differences are similar to those of people with impulse control disorders, such as OCD, addictions and antisocial personality disorder.

Pedophilia could be a byproduct of other co morbid psychiatric diseases. These brain abnormalities may have been formed by abnormal brain development. However, post-traumatic stress disorder also causes these types of brain abnormalities. Traumatic experiences in the pedophiles early life could have caused this atypical development (Hall & Hall, 2007).

Neurological Differences

Other neurological differences found in pedophiles included lower intelligence levels and the lower the intelligence level, the younger the preferred victim.

A substantial number of studies have indicated that pedophiles have cerebral abnormalities found in the temporal lobes (Hucker et al., 1986). Many Serotonin agonist differences were also found in pedophiles over tested control subjects.

Also found was an increased level of pedophilia in those people who sustained serious head injuries as young children, especially prior to age six. Another finding was that more pedophiles had mothers with psychiatric illnesses than the average person (Hall & Hall, 2007).

Some pedophiles were also found to have chromosomal abnormalities. Out of 41 men studied, seven of them were found to have chromosomal abnormalities, including Klinefelter syndrome, which is a condition in which a male will have an extra X chromosome in their genetic code (Berlin & Krout, 1994).

Environmental Factors

The environmental factors involved in pedophilia must also be considered. There is much controversy over whether or not being sexually abused as a child causes that child to grow up to be a sexual abuser. Statistics do weigh out indicating, that in general, more people who abuse children as adults were abused themselves as children.

The range is anywhere between 20% and 93%.

What would the reasons be for this happening? Theorists have proposed that perhaps the pedophile either wants to identify with his abuser or conquer his feelings of powerlessness by becoming an abuser himself, or maybe the abuse itself is somehow imprinted on the psyche of the abused (Hall & Hall, 2007).
Some scientists hold to the view that pedophilia really is not that much different from other mental illnesses, other than in how its deviant behavior is manifested. Like other troubled people, most sex offenders have problems establishing satisfying intimate sexual and personal relationships with their peers (Lanyon, 1986).

Developmental Issues

Other developmental issues occurred in the lives of pedophiles more often than the general population. Sixty-one percent of pedophiles repeated a grade or were enrolled in special education classes (Hall & Hall, 2007).

As mentioned earlier, it was found that more often than not, pedophiles had lower IQs than other people. Some theorists propose that pedophiles have arrested psychosexual development, caused by early childhood stress, which has caused their development to be “fixated” or “regressed” and is manifested in their sexual preferences for children.

Perhaps these early stressors caused an incomplete maturity process in these individuals which keeps them irrationally young in mind (Lanyon, 1986). Conceivably, that is why so many pedophiles identify more with children and view their behavior as completely acceptable.

Pedophilia is similar to certain personality disorders because the individual with the disorder is very self-centered, treats children like objects for his pleasure and does not really suffer personally with emotional distress (as is the case with many mental illnesses.)

Pedophiles, on the whole, seem to really believe that their behavior is normal, yet they must hide it because conventional society does not accept it. Pedophiles are convinced that they are doing a good thing when they molest children and that the children actually enjoy the relationship.

It has been speculated that pedophiles have not developed properly and are “fixated” or “stuck” at a certain stage of development mentally, while their hormones and physical bodies matured typically. Because of this conflict, the adult-child that the pedophile has grown up to become still relates to children better than adults.