A Developmental Taxonomy of Juvenile Sex Offenders for Theory,Research,and Prevention

A person-oriented approach to sex offending

Although between-group and within-group differences have been the focus of clinical and empirical research with JSOs, little attention has been given to within-individual changes over time or patterns of development. Criminal career researchers (e.g., Blumstein, Cohen, Roth, & Visher, 1986) and developmental criminologists (e.g., Loeber & LeBlanc, 1990) have called researchers’ attention to the need for and importance of studying within-individual changes in offending, but their call has not been taken up in the field of research of juvenile sexual offending until very recently (Hendriks et al., 2012). To study within-individual changes in offending, a longitudinal view of the sequence of crimes committed by an individual is required. Such a sequence is characterized by an onset (activation phase), a plateau where escalation and aggravation may occur, and desistance manifested in a slowing down of the activity before eventual termination (Lussier, 2005). Time and change are thus two components of a developmental approach to juvenile sex offending that require a longitudinal approach with repeated measurement of offending. This approach, referred to as the person-oriented perspective (Bergman & Magnusson, 1997), can help to capture distinctive patterns of onset, course, and desistance with distinct correlates and risk factors that may guide case management and clinical intervention (Lussier & Davies, in press). The aim is to disaggregate summary information about individuals and then identify patterns of individual development with the understanding that some patterns may be more prevalent than others (Bergman & Magnusson, 1997). Current empirical research aimed at explaining the offending behaviors of JSOs has mainly relied on a variable-oriented perspective. The variable-oriented perspective typically uses aggregate data and average series, which can obscure individual patterns of development (Von Eye & Bogat, 2006). As such, conclusions from the variable-oriented approach may apply to few individual cases, if not at all, or may be completely invalid. ² For the past two decades, a developmental person-oriented view of juvenile offending has been one of the most influential perspectives in the field of criminology and psychiatry.

Dual taxonomy of antisocial behavior

The dual taxonomy of juvenile offenders proposed by Moffitt (1993) is an example of a person-oriented approach. The dual taxonomy has been the subject of numerous empirical examinations generally supportive of the model (e.g., Piquero & Moffitt, 2005), but also subject to reformulation (e.g., Moffitt, Caspi, Harrington, & Milne, 2002), comments, and critiques (e.g., Sampson & Laub, 2005; Skardhamar, 2009). Moffitt’s (1993) taxonomy distinguished a group of life course persisters (LCPs) and a group of adolescent-limited (AL) offenders. The taxonomy includes several predictions about developmental antecedents, individual differences, and familial environment, but also the course of delinquency and crime (e.g., Lussier, Farrington, & Moffitt, 2009). More specifically, Moffitt (1993) argued that LCPs represented about 5% to 10% of a male birth cohort. On one hand, the LCPs had a childhood onset of conduct disorder, an earlier onset of delinquency, a more pronounced pattern of offending versatility and aggravation, a tendency to specialize in person-oriented offences (e.g., assault, intimate partner abuse), and a much greater likelihood to persist into adulthood than the AL group. Members of the AL group, on the other hand, were described by a late onset of offending with a tendency to specialize in property and statutory offences, and they typically desisted from offending by late adolescence. Moffitt (1993) convincingly argued that during adolescence, the LCP and AL groups might be virtually undistinguishable in terms of their offending, thus creating a challenge for clinicians and practitioners involved in the case management and treatment of these youth. It is likely that a similar situation may characterize JSOs, which has contributed to the proliferation of risk assessment tools to guide clinicians distinguishing the sexual recidivists from the nonrecidivists (e.g., Viljoen, Elkovitch, Scalora, & Ullman, 2009).

Longitudinal studies have shown that the dual taxonomy might be too restrictive and should be expanded to account for other patterns, such as common offenders and the low chronic offenders. In fact, longitudinal studies of offending patterns of youth have generally found between three and five trajectories of offending (Piquero, 2008; Tzoumakis, S., Lussier, P., LeBlanc, M., & Davies, G. 2011). Of importance for the current study, Moffitt’s LCP group were hypothesized to be most likely to escalate to rape and sexual assault (also see Lalumière et al., 2005). Moffitt (1993) argued that for LCPs, rape and sexual assault would be another manifestation of their antisociality through a complex process of heterotypic continuity (also see Lussier et al., 2007). This is reminiscent of the antisocial JSO group identified by Becker (1998) and Butler and Seto (2002). The LCP syndrome is unlikely to characterize all JSOs. Research suggests that no more than 40% of JSOs meet the criteria of a conduct disorder (e.g., France & Hudson, 1993; Långström & Grann, 2000; Seto & Lalumière, 2010). The proportion of child-onset and adolescent-onset conduct disordered JSOs remains unknown. Whether the other three-fifths of JSOs would be characterized as AL is questionable on several grounds but deserves some consideration for the current study. The AL group was initially described as adolescent-onset offenders who were involved in crimes that matched their desire for an adult status (e.g., driving without a license, property theft) rather than violent or person-oriented offences. This prediction is therefore counterintuitive to the idea of AL offenders committing sex crimes. Some researchers have objected to this view (Lalumière et al., 2005; Seto & Barbaree, 1997), arguing that members of the AL group may escalate their antisocial behavior to sexual coercion by, among other things, mimicking the behavior of LCP offenders. Based on this hypothesis, it would be expected that a relatively high proportion of AL offenders would be involved in gang rape.

Although the study of general offending careers is informative, it does not completely solve the issue of the association between nonsexual and sexual offending. Said differently, are the two taxa proposed by Moffitt (1993) adequate representations of the offending patterns of JSOs? Furthermore, although Moffitt’s taxonomy was aimed at describing patterns of antisocial behaviors, it is unclear whether the dual taxonomy also describes sexual offending patterns. Lussier and Davies (2011) examined the (nonsexual) violent and sexual offending trajectories separately for a group of adult sex offenders. There was much synchronicity between violent and sexual offending at the low-rate but not at the high-rate of offending. Thus, low-rate violent offenders were also low-rate sex offenders, but high-rate violent offenders were not high-rate sex offenders, and vice versa. This study suggested that high-rate sex offending might be a distinct phenomenon apart from high-violent offending. It appears, therefore, that synchronicity of offending between different types of crime becomes less significant and less important as the volume and rate of a particular form of crime increase. This point was also shown in the Lussier, LeBlanc, and Proulx (2005) study of adult sex offenders where synchronicity varied across offender types: The rapists charged for the most sex crimes were also those charged for the most property and violent crimes. This finding was not replicated for child molesters, where the most prolific sex offenders were not the most prolific in other crime types. This suggests that the criminal activity of chronic child molesters was more specific to sex crimes against children. It is unclear, however, whether the same findings apply to JSOs. Taken together, these findings raise questions as to whether or not the LCP group identified by Moffitt (1993) are also high-rate persistent sex offenders and whether the sex offending of the AL group is also limited to the period of adolescence.

Dual taxonomy and juvenile sex offenders

Moffitt’s (1993) taxonomy of antisocial and criminal behaviors represents a starting point for the elaboration of a classification model of juvenile offenders. This taxonomy draws from several themes: (a) that sexual offences committed by youth are first and foremost crimes and not necessarily manifestations of sexual deviance (Smallbone, 2006), (b) that there is a significant presence of conduct disorder, antisocial personality, and delinquency in the youths’ backgrounds (e.g., Butler & Seto, 2002; France & Hudson, 1993; Seto & Lalumière, 2010; Van Wijk et al., 2006); (c) that JSOs who recidivate are more likely to be rearrested for a nonsexual crime (Caldwell, 2002; Hendriks & Bijleveld, 2008; McCann & Lussier, 2008); and (d) that the criminal behavior preceding and following a sex crime is mainly nonsexual in nature (Van Wijk et al., 2007). Accordingly, sex crimes committed by JSOs are more often than not committed in isolation as part of a more general nonsexual offending pattern. The extent to which the taxonomy represents both the nonsexual and sexual offending trajectories remains unclear. In that regard, van den Berg, Bijleveld, and Hendriks (2011) and Hendriks et al. (2012) established that the dual taxonomy does not account for general offending trajectories of JSOs in the Netherlands. More precisely, their research found empirical evidence of five general offending trajectories in a sample of Dutch JSOs; (a) low chronic (33%), (b) AL (50%), (c) high declining (4%), (d) late-onset AL (6%), and (e) high chronic (8%). The AL somewhat mirrored the pattern of AL as hypothesized by Moffitt in terms of the rate of offending from early adolescence to adulthood. This group, however, accounted for only 50% of the sample of convicted JSOs. Of interest, the findings also showed that child abusers were more likely to follow an AL track of delinquency as opposed to peer abusers, suggesting a link between the type of sex offence committed and general offending trajectory. The AL track of offending and child abuse is counterintuitive to portraying AL offending as more transitory and contextual (Moffitt, 1993) whereas child molestation in youth has often been associated with cognitive deficits and poor outcomes (e.g., Worling & Långström, 2006). None of these studies found evidence of a LCP group. Although the findings are interesting, they do not inform about the patterns that are specific to sexual offending as the van den Berg et al. (2011) and the Hendriks et al. (2012) study did not examine sexual offending trajectories separately from nonsexual offending. Hence, the extent to which the sexual offending trajectories of JSOs follow the taxonomy remains unclear.

Taxonomy and the onset of sexual offending

The patterns of sexual offending suggest that the two offending trajectories can be differentiated in terms of the onset of sexual offending. The findings showed that HRSD JSOs had an earlier onset than those found in the AL group. The pattern of onset found for the two groups is intriguing given that age of onset in sexual offending has not been subjected to much empirical scrutiny in the scientific literature. Recently, using retrospective data in a large sample of JSOs, Carpentier et al. (2011) found that early starters (i.e., onset prior age 12) were more likely to exhibit violent behaviors in early childhood as well as child sexual problems such as voyeurism, frottage, and compulsive masturbation prior to the onset of sexual offending. These youth were also more prone to aggressive behavior during adolescence as opposed to late starters. The highest rate of sexual offending for the HRSD was found at the earliest point analyzed, that is, at age 12. We suspect that the group showing an earlier onset of sexual offending might be characterized by childhood sexual problems. More precisely, sexual offending of the HRSD group might be in continuity with sexual problems in the preceding developmental periods (i.e., prior age 12) not analyzed in the current investigation. Few empirical studies have examined the developmental course of sexual behaviors in children (e.g., Friedrich & Trane, 2002). Recent research with preschoolers revealed that boys from low-income families who present clinical symptoms associated with an externalizing spectrum disorder (e.g., ADHD) and who are more physically aggressive have a higher frequency of various forms of sexual behaviors (Lussier & Healey, 2010). The co-occurrence of high levels of physical aggression with child sexual problems could be among the developmental precursors of an early onset of JSOs. Research has shown that such behaviors are affected by pre- and perinatal risk factors. For example, substance use during pregnancy, and pregnancy and birth complications, are related to higher levels of offspring physical aggression and sexual behaviors (Lussier, Tzoumakis, Healey, Corrado, & Reebye, 2011). More research is needed to link the developmental course of sexual behaviors and the developmental course of sex offending.

Taxonomy and sexual recidivism in youth

Empirical studies have not produced convincing evidence that sexual recidivism in youth can be predicted efficiently using current risk assessment methods (Caldwell, 2002; McCann & Lussier, 2008; Viljoen et al., 2009). One explanation is that the presence of two different types of juvenile sexual recidivists may have confounded the findings of previous sexual recidivism studies. Indeed, both the HRSD and AL JSOs include youth at risk of sexually reoffending during the period of adolescence. This highlights difficulties and challenges associated with clinical assessment of juvenile offenders. More precisely, among juvenile sexual recidivists, some offenders will desist from sexual offending after reaching adulthood (AL) whereas others will persist beyond that point (i.e., HRSD). Hence, the current findings suggest that there might be two types of sexual recidivists among JSOs. Prior recidivism studies have not examined whether the predictors of sexual recidivism among the AL JSOs are similar to or different from those of the HRSD group. Therefore, it is possible that persisting transitory risk factors associated with adolescence may increase the risk of sexual recidivism in youth for the AL group, whereas the accumulation of early deficits may increase the risk of sexual recidivism for the HRSD. In that regard, Lalumière et al. (2005) distinguished the young male syndrome from the LCP and psychopathy groups of sexual aggressors. From this model, those with the young male syndrome may resemble our AL group in that their sexual offending may be driven by temporary difficulties finding a consenting sexual partner. For the LCP and the psychopathy group, as with our HRSD, sexual assault may be reflecting a stable predisposition and more stable individual differences. Sexual recidivism studies are of limited value in informing case managers, risk assessors, and treatment providers about the offending trajectories of these youths. The difficulty for these practitioners in differentiating the AL and the HRSD is further reinforced by the fact that both groups are found among child abusers, peers abusers, and group offenders. Future empirical studies should examine the predictors of sexual recidivism in adolescence for both groups and determine whether risk assessment protocols are as effective for HRSD and AL offenders.

Taxonomy and persistence in adulthood

Our findings demonstrated that sexual recidivism in youth and criminal persistence in adulthood are two separate aspects of criminal activity of JSOs. Indeed, although both the AL and the HRSD groups included juvenile sexual recidivists, only the latter group persisted sexual offending as adults. The proportion of JSOs following a track of HRSD (about 10%) is in line with sexual recidivism studies that follow youth well into adulthood (e.g., Hagan, Gust-Brey, Cho, & Dow, 2001; Hendriks & Bijleveld, 2008). This finding underscores once again the limitations of current sexual recidivism research with JSOs, in which such a distinction is rarely made (McCann & Lussier, 2008). Considering the case of the HRSD, it is unclear whether risk factors that are associated with sexual reoffending in youth (e.g., Hendriks, 2006; Kenny, Keogh, & Seidler, 2001; Prentky, Harris, Frizzell, & Righthand, 2000; Worling & Långström, 2006) are the same factors that contribute to the persistence of sexual offending into adulthood. In that regard, Knight, Ronis, and Zakireh (2009) recently demonstrated that JSOs who persist in adulthood were more likely than nonpersisting juvenile offenders to show evidence of sexual preoccupation and compulsivity, poor perspective taking, (adult/child) pornography use, hostility toward women, and superficial charm and grandiosity. Their study also demonstrated that youth who did not persist had more problems at school, showed less guilt, and experienced the same level of angry thoughts and fantasies as compared to the persisters. Hence, the AL sex offending track may include JSOs presenting state-dependent features (e.g., risk taking, entitlement, and strain) that are exacerbated during the transitory period of adolescence, whereas the HRSD group may present trait-like features (e.g., callousness, hostility, hypersexuality) that are more likely to persist into adulthood (also see Lalumière et al., 2005; Seto & Barbaree, 1997).

It is interesting that a subgroup of youth following the AL track of sex offending continued to offend as adolescents, but only for nonsexual crimes. Lack of persistence in sex offending is not necessarily indicative of a lack of persistence in other forms of criminal activity. It could by hypothesized that for some members of the AL group, the conviction for a sex crime in youth had long-lasting negative consequences such as a criminal record and involvement with other adjudicated youth, which may have led to nonsexual criminal involvement in adulthood (see Figure 3). This hypothesis raises issues about focusing solely on the risk of sexual offending in adulthood as an outcome measure for JSOs. Previous recidivism studies with JSOs have found that if these youth do reoffend, it is most likely a nonsexual crime (e.g., Caldwell, 2002; Hendriks, 2006; McCann & Lussier, 2008; Nisbet, Wilson, & Smallbone, 2004). Our findings reinforce this finding. Of the 112 AL sex offenders in our study with a pattern of nonsexual offending in youth (late bloomers, high-rate offenders, and AL offenders), 60 (53.6%) persisted their nonsexual offending in adulthood. Hence, in spite of desisting from sexual offending, their nonsexual offending persisted. Their sexual offending might have been more transitory, but not their delinquency. Similarly, of the 16 HRSD with a pattern of nonsexual offending in youth, 13 (81.3%) persisted their nonsexual offending in adulthood. The study, therefore, suggests that an intervention scheme that does not take into consideration both their delinquent involvement and their sexual offending may not have the desired effect in preventing recidivism (also see Hendriks, 2006). Future studies should examine the risk factors of persistence in nonsexual crimes for both AL and HRSD offenders.

Taxonomy and crime specialization

It is generally accepted among criminologists that sex offenders do not tend to specialize in sex crimes (e.g., Carpentier et al., 2011; Lussier, 2005; Smallbone, 2006; van den Berg et al., 2011; Van Wijk et al., 2007; Zimring, Piquero, & Jennings, 2007). Specialization in sexual offending refers to the presence of a sustained pattern of offending where sex offences are predominant (e.g., see LeBlanc & Fréchette, 1989). Hence, an individual having committed one sex crime without having been involved in other forms of offending (sometimes referred to as the sexual-only type) does not constitute a pattern of crime specialization. Our findings suggest that AL offenders are less likely to become sex crime specialists. In fact, 237 of the 446 (53%) AL sex offenders are characterized by a low level of sexual criminal activity limited to the period of adolescence and a very low rate of nonsexual criminal activity until their 30s. The second most important group among the AL sex offenders (n = 97, 22%) are characterized by a late start of their nonsexual offending in adulthood, suggesting that although they persist in their offending, it is characterized by crime switching (i.e., from sexual offending to nonsexual offending). The group most at risk of specializing in sex offending can be found in the small group of HRSD offenders. Indeed, for half of this group (27 out of 52, or 52%), their offending was limited to sexual offending. Therefore, if trait-like features were responsible for the offending behavior of HRSD, it is reasonable to think that it would have been a trait more specific to sexual offending. HRSD offenders may include youth at risk of developing trait-like features associated with the propensity to commit sexual crimes, such as deviant sexual interests, sexual compulsivity, and sexualization (Lussier et al., 2005). Research has shown that sex crime specialists are responsible for a higher number of sex crime events; they offend against a higher number of victims and are more skilled at avoiding detection and apprehension (Lussier, Bouchard, & Beauregard, 2011). To keep this in perspective, this pattern of high-rate sex offending and crime specialization was found for 27 cases out of a sample of 498 convicted JSOs (5.4%). These cases are clearly not the norm. The presence of AL offenders whose sexual and general offending is very limited, combined with the presence of a specialization pattern found in the HRSD group, might explain Seto and Lalumière’s (2010) observation that JSOs, as a group, have less extensive general criminal records than juvenile nonsexual offenders. More research is needed to understand this small subgroup of JSOs at risk of specialization in sex crimes and factors that may contribute to specialization in sexual offending.

Taxonomy and desistance

Desistance from sexual offending remains an understudied area of investigation (e.g., Kruttschnitt, Uggen, & Shelton, 2000; Laws & Ward, 2011). In support of the discontinuity hypothesis (e.g., Hendriks, 2006; Miner, 2007; Zimring, 2004), the current longitudinal study highlighted that desistance from sexual offending is the norm in the vast majority of JSOs. More specifically, the study highlighted how desistance occurred in both AL and HRSD groups, but both groups desisted at a different pace and at different time points. These findings suggest that the AL and HRSD groups may be desisting for different reasons under different circumstances. For the AL group, sexual offending may be attributable to more transitory and circumstantial factors that may not persist beyond adulthood. The HRSD group, however, may be characterized by specific stable individual factors that can persist beyond adolescence and into adulthood and continue to put these individuals at risk of committing a sex crime. Empirical research has identified several areas of investigation (such as self-regulation deficits, sexual regulation, cognitive distortions supportive of sex offending, insecure attachment, etc.; e.g., Beech & Ward, 2004), but these traits do not explain why, and under which circumstances, individuals characterized by such predisposing factors may desist from sexual offending. Empirical research should investigate the factors that are operating for both AL and HRSD offenders, including both stable as well as dynamic characteristics such as employment, romantic relationships, addiction, and the like.

A life course perspective may be warranted here as their desistance occurs at two different points in their lives, that is, around 18 years old for the AL group and in the early 30s for the HRSD group, which is where our timeline stops. This is reminiscent of Moffitt’s (1993) dual taxonomy of antisocial behavior distinguishing a group of AL young offenders desisting when reaching adulthood from a group of LCPs persisting well beyond that point. The study findings showed much nonsynchronicity between patterns of sex offending and nonsexual offending, suggesting that a general model of desistance from delinquency may not apply to sex offending. Said differently, desistance from nonsexual offending may not necessarily mean that an individual will desist from sex offending. Moffitt’s taxonomy does not inform about the factors operating on different crime types, providing instead an explanation for the desistance pattern of AL offenders. Some JSOs desisted from sexual offending in adolescence but persisted their nonsexual offending in adulthood, whereas other youth desisted from nonsexual offending in adolescence but persisted their sexual offending in adulthood. Such patterns cannot be explained by Moffitt’s dual taxonomy. Different turning points and life events may affect the course of their sexual offending. For example, life events in late adolescence and emerging adulthood (e.g., entry in college/university, labor market) may provide new social environments and social opportunities such as prosocial male and female peers who may trigger self-identity change and, in turn, act as protective factors for the AL group, but likely not for the HRSD group (Laws & Ward, 2011; Sampson & Laub, 2005).