**2. Aetiology of sex offending**

In the past, sex offender literature has largely focused on biological and psychological roots of offending making individual pathologies and early trauma the most common explanations for sexual offending. Traditional theoretical views on sexual offending describe sexual offending through trait-like features such as cognitive distortions, low victim empathy, deviant sexual preferences, poor attachment style, sexual regulation. We will here briefly present some of the most used theoretical explanations regarding sex offending.

One of the major concept used in explanations of sexual offending is paraphilias who are defined as sexual disorders characterised by intense, sexually arousing fantasies involving either nonhuman objects, suffering or humiliation of oneself or one's partner, children or other nonconsenting persons [11]. Most common paraphilias are paedophilia, voyeurism, transvestic disorder and exhibitionism [12]. However, it was found that unlike problems such as depression or anxiety, most cases of sexual offending (rape, child molestation, etc.) are not associated with any particular cluster of covarying signs and symptoms [13]. Moreover, even though some individuals who commit sexual offences against children are diagnosed with paedophilia, a mental disorder characterised by deviant sexual interests in children and some may have a paraphilia of some type, typically, this is not the case for all child sex offenders. [13]. Attachment theory, however, points out that sexual deviance is a consequence of the loss or emotional distress and intimacy deficits [14].

The psychodynamic theory explains sexual deviance as an expression of the unresolved problems experienced during the stages of development, and sexual deviancy occurs when the *id* is overactive [14]. The function of *id* is to operate unconsciously and to impel the organism to engage with need satisfying activities which are experienced as pleasure. However, this explanation fails to **address the cultural context of human development** [15]. Similarly, biological theories focus on abnormalities in the structure of the brain, level of hormones, genetics, and deficits in the intellectual functioning of sex offenders. Many studies have shown abnormalities in the brain of some perpetrators, but there is insufficient evidence to support more generalisation of the results [16]**.**

Sex offending can also be studied through feminist theories focusing on the structure of the relationship between the sexes and the disparity of power between a man and a woman [16]. In general, feminist theories on child sexual abuse are divided into radical feminist perspective and post-modern perspective. Radical perspective centres on the patriarchal nature of (Western) society. Patriarchy has been defined by radical feminists as the world view that seeks to create and maintain male control over females. This perspective emphasises that sexual abuse is a representation of the patriarchy and the power that men have over women and that all men are socialised to hold attitude and exhibit behaviours that are associated with sexual offending. However, this perspective was criticised because of the lack of empirical scope [17]. The post-modern perspective rejected the radical perspective and established that men who sexually abuse are neither outside the society nor reducible to it and that they may know exactly what they are doing, but some offenders may not. This perspective was as well criticised because it is vague on what their theoretical position on sexual violence is [17].

Evolutionary theories, however, explain the diversity of human behaviours, including the aggression of sexual offenders as a way of adapting to changes in the environment. The evolutionary settings explain sexual aggression on sexual selection and reproductive strategies, whereby as one of the sexual strategies they cite the compulsion of sexual coercive is also present in the animal world as one of the reproductive strategies. The criminal offence of rape within these theories is a result of the inability of men to win a partner by more appropriate methods [16].

More influential theories in social sciences described sexual offending through cognition and behaviour. Behavioural theories suggest that deviant sexual behaviour is the result of learned behaviour. They assume that sexual excitement plays a crucial role in sexual offences. Sexual satisfaction and lack of negative consequences of sexually deviant behaviour increase the likelihood that such behaviour will continue. If the negative effects are strong enough, the behaviour will decrease [16]. However, many male sex offenders lack deviant sexual arousal patterns [18] and other traits such as the lack of empathy for the victim or remorse which in some individuals may also play a role in the development of deviant sexual behaviour patterns [16].

Cognitive theories suggest that cognitive distortions are the main cause of deviant sexual behaviour and that "concealed" opinion leads to "distorted" behaviour [16]. Cognitive distortions are often referred to as offence-supportive attitudes, or cognitive processing during an offence sequence, as well as post-hoc neutralisations or excuses for offending [19]. The cognitive-behavioural theory addresses how offenders' thoughts affect their behaviour: focus on how sexual offenders diminish their feelings of guilt and shame by rationalising them through excuses and justification [14]. Although many offender rehabilitation programmes focus on eliminating cognitive distortions, the relationship between cognitive distortions and future crime is not clear and it seems cognitive distortions may not be what causes fallacious thinking at all because, outside the criminal context, "making excuses" for one's behaviour is widely viewed as a normal thing [19].

Social learning theories explain how children who are victims of sexual abuse become perpetrators of sexual offences as adults. Also, this theory states that sexually explicit materials can contribute to committing sexual offences. Furthermore, victim's age at the beginning of abuse, the relationship between the perpetrator and the victim, the type of sexual act, the amount of coercing used, and the duration and number of victimising events all have a crucial role in the connection of acts of sexual offences and subsequent acts of sexual delinquents [16]. This theory is most often criticised because there is little evidence to suggest that children who are victimised will become abusers themselves [20]. Furthermore, direct link between the use of pornography and sexual violence was never confirmed; however, some studies suggest there might be some connection between pornography and attitudes that support sexual aggression [16].

One of the limitations of these trait-like approaches is that it comes at a cost of a broader view of sexual offending. Moreover, individual pathologies-based explanations are not well suited for a developmental and longitudinal perspective of causes for this kind of behaviour. They have also contributed to sex offender researchers emphasising the differences, rather than searching for the similarities between sexual and nonsexual offending [6]. Criminal career approach provides a more developmental point of view explaining how sexual offending starts, develops, and stops as well as whether such distinctions are theoretically, clinically, and/or policy relevant [2]. In other words, maturation and dynamic theories assume that the same mechanisms underlie the behaviour of all offenders while life-course criminology emphasises the need to use a more broader view on the causes of sex offending as well as to find similarities between the perpetrators of these crimes rather than differences.

The most important theoretical question that needs to be answered when studying sex offenders through criminal careers is whether sex offenders should be regarded as similar or different from non-sexual offenders in terms of the aetiology of their offending behaviour. Consequently, there are two possible ways to consider sexual offending- that it is different from non-sexual offending and that it is an integral part of the general offending repertoire.

If studied separately, one possibility is to distinguish adolescence-limited from persistent sex offenders. This way of studying offenders gained its popularity in the 1990s with Moffit's Dual Taxonomy theory [7]. This theory states that adolescencelimited antisocial behaviour individuals have brief criminal careers, lack consistency in their antisocial behaviour across situations and may also have irregular, crime-free periods. Adolescence-limited delinquents are likely to engage in antisocial behaviour in situations where they estimate they could gain profit, but they also abandon antisocial behaviour when prosocial behaviour is more rewarding.

Adolescence-limited offenders usually start offending by the ways of three distinctive conditions: motivation, social mimicry and reinforcement. Social mimicry is a term taken from the ethology and is loosely connected to the social mirroring theory. Adolescents often mimic the behaviour of their life-coursepersistent peers in order to gain the same benefits (i.e., status in the peer groups; friends, etc.). In other words, adolescence-limited offenders commit criminal offences if they can gain from them, and if such behaviour is reinforced by their peers. With a change in their circumstances, for example, starting college or starting a job, they will usually stop offending [7].

Individuals that fall under the category of life-course-persistent antisocial behaviour exhibit antisocial behaviour at an early age. For example, biting and hitting at age 4, shoplifting and truancy at age 10, selling drugs and stealing cars at age 16, robbery and rape at age 22, and fraud and child abuse at age 30; the underlying disposition remains the same, but its expression changes form as new social opportunities arise at different points in development. The Dual taxonomy theory, however, does not suggest that all specific behaviours in childhood will be predictive of criminal behaviour in adulthood, but that it might be associated with behaviours that are conceptually consistent with the earlier behaviour [7].

Beyond young adulthood, the antisocial disposition of life-course-persistent may be expressed in a form that is not yet well-measured (e.g. neglect and abuse of family members). According to this theory, it is necessary to investigate the roots of antisocial behaviour in the early life of life-course-persistent offenders. Moreover, some of the causes for life-course-persistent offending are neuropsychological (disruption in the ontogenesis of the fetal brain, minor physical anomalies, maternal drug abuse, poor prenatal nutrition, exposure to toxic agents, brain injury because of complication during delivery), variability in infant temperament, developmental milestones and cognitive abilities, exposure to criminogenic environment or inconsistent discipline. Thus, over the years, an antisocial personality is slowly constructed. Likewise, deficits in language and reasoning are incrementally elaborated into academic failure and insufficient job skills. Over time, all the problems accumulate, and an individual has fewer options for change. This theory of lifecourse-persistent antisocial behaviour emphasises the constant process of reciprocal interaction between personality traits and environmental reactions to them [7].

However, if sex offending is studied combined, the question is to what extent sexual offending (or which type of sexual offending) is characteristic of a particular overall offending trajectory. Furthermore, it might be necessary to study sexual offenders by dividing them into different offence types as they may be stemming from different causal processes and thus it would be best to consider their different developmental pathways [6].

Current research suggests that there are some significant differences between sex offenders and non-sexual offenders. For example, the prevalence of general delinquency peaks in adolescence while sex offenders have two peaks in offending, one in adolescence and on in the mid to late 30s [6, 21, 22]. Also, sex offenders show continuity in general offending and antisocial behaviour, but low continuity in sexual offending [22]. This finding resonates with the finding that delinquency is usually just a part of a larger behavioural repertoire consisting of potentially harmful behaviours such as substance misuse [21]. Similarly, non-sexual offences usually precede sexual offences and specialisation in sex offending does not increase in adulthood [6, 22]. Therefore, criminal career offers an interesting way of studying offending patterns by looking into the four key dimensions (participation, frequency, seriousness, and length [3, 4, 9, 10, 23] and related constructs such as escalation, specialisation, co-offending, intermittency, and others [2, 9, 24, 25].
