Introduction

National and international victimisation data demonstrate that intimate forms of violence, such as domestic and family violence, are gendered (Tarczon & Quadara, 2012; World Health Organization, 2002). However in both academic and popular discourses there is a lively debate about the possibility of men's and women's equivalent use of physical, emotional and psychological violence, with some researchers arguing that there is no gender difference in the perpetration of intimate partner and domestic violence (Kar & O'Leary, 2013; Straus, 2012). The debate centres on the notion that domestic violence is gender neutral - rather than a gendered crime in which men are by and large the perpetrators and women and children make up the majority of victims. This debate can be dangerous as it may promote men's denial of their violence toward women and denial of women's experiences of violent victimisation. Denial can continue the cycle of power and control that is a feature of men's violence against women.

While sexual violence has tended not to be a feature of these debates, its gendered nature (as demonstrated by the statistics) is challenged and undermined when instances of female sex offending are reported in the public domain. Like the gender symmetry debate in domestic and family violence, the occurrence of female sex offending is seen to invalidate the empirically supported notion that sexual assault is a gendered crime. It is important therefore to present what is currently known about female sex offenders in an examination of available data.

The importance of research on female sexual offending is highlighted by the difficulty in conceptualising it (Brayford, 2012).¹ In the existing research/literature, there is no real clarity around what motivates females to sexually offend. However there is often a rejection of the idea of women having the potential for violence and deviant, coercive sexuality (Brayford, 2012). There is an over-reliance on gender in discussing female sex offenders (specifically in the media and more broadly on a social/cultural level) that can often lead to the notion that female sex offending is less harmful - psychologically and physically - than male sex offending.

Gender relates to the social characteristics attributed to men and women that can often be more prescriptive than descriptive of actual characteristics and behaviour. Although gender is an important conceptual tool there may be an over-reliance on gendered stereotypes in the public domain. Conversely, gender may play a role in how men and women sexually offend and ways that gender may conceal women's offending. It is here that the difficulty lies - and a review of the literature does not completely undo this difficulty.

Little is known about female sex offenders, and what empirical work has been done is in the initial stages of identifying characteristics associated with female sex offenders (Fisher & Pina, 2013). Although prevalence rates are variable, the general consensus is that around 5% of sex offences are committed by women (Cortoni & Hanson, 2005; Cortoni, Hanson, & Coache, 2010). Much of the work - which began in earnest in the 1980s - has limitations due to being conducted mainly with known offenders who are in the criminal justice system, or with very small clinical samples (Vandiver & Walker, 2002). Small sample sizes occur because there are only very small populations of female sex offenders, as opposed to much larger populations of male sex offenders.

There currently appear to be no research summaries that bring together everything that is known about female sex offenders. This Research Summary will explore the current literature - predominantly from 2000 onward - and outline what is currently known about female sex offenders. Tables of data related to offence and offender characteristics will be presented to bring together the current available empirical evidence. The impacts on victims and issues related to disclosing sexual abuse perpetrated by women are also included.

Prevalence of female sex offenders

Prevalence statistics are difficult to estimate accurately as there is a number of issues relating to data collection and reporting of sexual violence (Cortoni et al., 2010). Firstly, police statistics will usually indicate lower rates of sexual violence than victimisation surveys of the general population (such as the Personal Safety Survey by the Australian Bureau of Statistics [ABS]), due to the underreporting of sexual assault to authorities (Vandiver & Walker, 2002). Secondly, victims may face many barriers to disclosing sexual abuse and assault and for this reason prevalence statistics may never accurately be reflected in any source. Finally, as female sex offending is only starting to be measured and various definitions are used to define sexual offences, it is difficult to accurately report prevalence.

Cortoni and colleagues (2005; 2010) offer the most comprehensive prevalence statistics on female sexual offending - having analysed official reports in five countries, including Australia. When averaged across all countries, official records data show that 4.6% of offences were committed by women and victimisation survey data 4.8% (Cortoni et al., 2010, p. 388). The details are presented below. Some of the data in Table 1 relates to both child and adult victims.

In an effort to bring clarity to the issue, Denov (2003) used data from 15 separate studies and found disparity in data collection, differences in terminology regarding what constitutes a sexual offence (e.g., a sexual offence may be indecent exposure in one study and penetrative sexual assault in another), and small sample sizes - all affect the capacity to definitively report the prevalence of female-perpetrated sex offences. However, these issues affect all sex offence statistics - as does the issue of underreporting of offences due to significant barriers related to fear of not being believed, shame, fear of the perpetrator, and uncertainty (Fileborn, 2012; Foster, Boyd, & O'Leary, 2012; Stathopoulos, 2012; Wall, 2012).

Notes: Studies as cited in Cortoni & Hanson, 2005. ^a This may relate to indecent exposure or other such acts. ^b Related offences include non-assaultive sexual offences such as procuring a child for pornography, grooming offences, and gross indecency (ABS, 2005).

Source: Cortoni & Hanson, 2005, p. 8.

Some further data from larger studies are included below, however, not all are nationally representative.

• The most recent Australian data on female sex offences based on official court records indicates that women committed up to 1.6% (or 45 out of 2,875) of all sexual offences in the period 2011–12 (ABS, 2013, Table 7).
• The 2001 National Incident-Based Reporting System (NIBRS), a source of crime reporting for the Federal Bureau of Investigations (FBI) in the United States, reported that female sex offenders made up 3.1% of all sex offenders (Vandiver, 2006).
• Vess (2011) reported that between 1.2% and 8% of all people charged with sex offences in the US, UK and Canada were women.² These rates were based on official sources of data (e.g., arrest rates). The rates for "those convicted of sexual assaults against children" that were female were between 1.5% and 4% of all child abuse convictions (Vess, 2011, p. 81).
• Figures based on 12,268 calls to a children's confidential helpline in the United Kingdom indicated that female sex offenders made up 17% of perpetrators reported by children (Elliott & Ashfield, 2011). Caution must be exercised in reporting this figure however, as the study is not a nationally representative prevalence figure.
• Dube et al. (2005) conducted a study into the adverse life effects for those with a history of child sexual abuse victimisation. The survey had 17,337 participants (7,970 male, 9,367 female). The population came from the Kaiser Permanent's Health Appraisal Centre in San Diego, US. The tool used was the Adverse Childhood Experiences survey. Findings indicated:
  • 1,276 males had experienced childhood sexual abuse (intercourse and non-intercourse). Of those, just under 21% had been abused by a lone female perpetrator and just over 18% by both male and female perpetrators; and
  • 2,310 females were victims of child sexual abuse. Of those, just over 2% had been abused by a lone female perpetrator and 3.6% by both male and female perpetrators.

Characteristics: Offender and offence

This section presents what is currently known about female sex offender characteristics and the sex offences they commit.

Table 2 presents data collected from multiple sources and demonstrates the patterns as they emerge and subsequent typologies that have been identified. The categories presented relating to relationship status, mental illness and cognitive ability, drug and alcohol use and misuse, and victimisation histories come from the data presented in the literature. The database used to source the journal articles on offender and offence characteristics was Web of Science, which houses social science, arts and humanities journals. Search terms included "female sex offender characteristics", "female sex offence characteristics", "female sex offender" and "female sex offence". Many of the articles cross-referenced each other and additional articles were found this way. All articles included in this section were published between 2000-13. The sources used are not exhaustive, however they are illustrative of the most common offender and offence characteristics found in the literature.

In Table 3 the categories of relationship to victim/s, number of victims, solo and co-offenders, and type of assault are taken from categories present in the literature on offence characteristics.

Table 2 demonstrates that some detected female sex offenders have high rates of mental health issues and alcohol and drug abuse issues. However, the most striking feature is a history of previous victimisation - which can often lead to mental health and substance abuse issues. Many adults who sexually abuse do have a history of childhood victimisation, however most people who were victimised in childhood do not go on as adults to sexually abuse (Cashmore & Shackel, 2013).

Offence characteristics reveal that female sex offenders tend to offend against those known to them, although there may be differences when they co-offend with a male accomplice. Female sex offenders are likely to be in a relationship with their co-offender and are more likely to use verbal coercion rather than physical coercion against a victim.

Offender and offence characteristics that are taken from criminal justice and clinical contexts may only reveal particular types of sexual offences committed by female sex offenders. The only study that sits outside of these contexts is a survey of 546 female college students conducted by Fromuth and Conn (1997). They found that 22 of the women surveyed had committed sexual offences when they were younger than 14. Two reported that they had used force. None of these assaults had come to the attention of authorities. They had mainly committed assaults against male children they knew, for example cousins, siblings and children the perpetrator was babysitting (Fromuth & Conn, 1997). Most of the offenders in this sample had a history of child sexual abuse victimisation. More community-based research may help to identify further characteristics of both offenders and the offences that don't appear in victimisation surveys or officially recorded administrative data.

Typologies

The utility of typologies of female sex offenders (as with all crimes/criminals) allows for greater detection, management and treatment (Vandiver & Walker, 2002). They can also be useful in determining treatment needs for victims. The first study to develop typologies was by Matthews, Mathews, and Speltz (1991). The typologies they created have remained stable and continue to be used today. Further research has allowed for subsequent types and sub-types to be identified. The typologies are usually based on offender and offence characteristics and can potentially describe the offence and the process and relationships by which the offending comes about (Vandiver & Kercher, 2004). Table 4 presents typologies of female sex offenders from the aforementioned research as well as others. It should be noted that sex offenders are a heterogeneous group and there will likely be some who overlap into different typologies (Oliver, 2007; Sandler & Freeman, 2007). Additionally, these categories are not exhaustive.

Some researchers build typologies on offender, offence and victim characteristics, others on arrest data, however Matthews et al. (1991) used offender motivation as a defining characteristic (Correctional Service Canada, 2008). Matthews et al.'s (1991) typologies have had the most utility in the field and have acted as a cornerstone from which to build more detailed sub-types. Horrocks (2010) noted that although other research into typologies, such as that conducted by Vandiver and Kercher (2004), is useful, it has limited utility due to its lack of explanatory motivational factors. Horrocks asserted that a lack of motivational factors meant "treatment and criminal justice providers have a reduced capacity to understand the offender and prevent re-offending" (Horrocks, 2010, p. 102).

The following types of sex offending perpetrated by females will be expanded on below:

• solo vs co-offenders;
• mothers who sexually abuse their children; and
• female paedophiles online.

The first type is important because women who co-offend with a male offender are the largest group in terms of officially recorded offences. Mothers who abuse their own children are thought to be extremely rare, however this abuse is more likely to be underreported and sometimes never disclosed (Lawson, 1993). Finally, women who use the Internet to abuse children or view child pornography are a new area of research in the field.

Solo vs co-offending female sex offenders

Vandiver (2006) undertook to isolate the differences between solo and co-offenders in a sample of 232 female sex offenders. This work interested her because previous research, including her own, demonstrated female and male sex offenders may have quite different motivations for their offending. Most co-offenders of female sex offenders are male, usually an intimate partner or husband. When it comes to solo female offenders, Gannon and Alleyne (2012) conducted a systematic review of research and found it was the women's offense-supportive cognitive distortions³ that motivated their offending. Table 5 includes some differences in solo and co-offending female sex offenders as outlined in the studies mentioned above as well as others.

Nathan and Ward (2002) engaged with the idea of a unique typography for co-offending female sex offenders based on a clinical study with 12 female child sex offenders. This study is of importance to the field because female co-offenders had previously been described as predominately coerced into their offending, or identified as women who had previously been abused "may re-enact[ing] their own abuse with children" (Nathan & Ward, 2002, p. 8). In Nathan and Ward's (2002) study, eight of the 12 female sex offenders in their sample had co-offended with their male intimate partner. The women under study revealed "jealousy", "revenge" and "rejection" as motivating factors in their sexual offending. Nathan and Ward noted:

a number of the female offenders experienced deviant arousal during the offence process, suggesting that sexually deviant interests and preferences may indeed motivate some women. (Nathan & Ward, 2002, p. 18)

They suggested a new sub-category for female sex offenders who work with a male accomplice called "male accompanied: rejected/revengeful" to capture those women whose offending was not coerced by a co-offender but instead motivated by power, control and anger issues. Some of this work goes to understanding the agency of women in their offending behaviour as an important conceptual tool in understanding female offenders (Morrissey, 2003). The identification of sub-types is important in informing treatment interventions, however caution must be exercised in reporting these findings as they are based on a very small sample of only 12 offenders. These findings should not be used to invalidate the experiences of women who are coerced into offending, possibly having already experienced child sexual victimisation themselves. It is important to acknowledge male coercion as an avenue for women's offending and then identify how to protect vulnerable women from such coercion.

Mothers who sexually abuse their children

Mother-son child sexual abuse

As outlined in the typologies section above, Lawson (1993) identified five types of maternal sexual abuse. Maternal abuse is considered to be an underreported form of abuse (Kelly, Wood, Gonzales, MacDonald, & Waterman, 2002; Rudominer, 2002). Men who were abused by their mothers usually will not disclose at the time of the abuse. They may eventually seek therapy for a range of problems (most likely impacts from the abuse) particularly if they reach crisis point (Foster et al., 2012). The disclosure usually comes out at this time (Lawson, 1993).

This means that mother-son abuse does not find its way on to police records but does in victimisation records, although it rarely appears as a large population due to methodological issues such as not identifying the relationship between perpetrator and victim beyond identifying they are related. A lack of empirical and official recorded evidence means not enough resources may be geared toward supporting victims. Additionally, there is little knowledge about mothers who sexually abuse sons, and therefore few ways in which clinicians can identify risk factors associated with maternal sexual abuse.

Mother-daughter child sexual abuse

Mother-daughter abuse has been a particularly difficult crime to conceptualise. Peter (2006) believes this is because feminist scholarship has turned away from understanding women who sexually abuse and the only narratives that exist for them are that they are "mad, bad, or victim" (p. 283). Peter (2006) expressed a belief in the importance of acknowledging women's capacity for violence and abuse. She warned that this should not be hijacked to mean that women are capable of the proportions of abuse perpetrated by male sex offenders as there is no evidence that suggests this. However, acknowledging women's capacity for violence validates victims and their experiences (Peter, 2006).

Peter (2008) wrote that mother-daughter abuse is very rarely reported, less so than other forms of abuse. She stated that:

despite the shift from the rigid binary of male-only offender and female-only victim, sexual abuse of a female child by an adult female was - and still remains - largely neglected in the literature. (p. 1034)

In speaking with eight victim/survivors of maternal sexual abuse, Peter (2006) stated "there is little space where survivors can locate or make sense of the violence - especially within the dominant constructions of motherhood and femininity" (p. 293). All eight victim/survivors were sexually abused by only their mother. Most of the female perpetrators (mothers) in this study had a history of child abuse victimisation. None of the eight female victim/survivors (daughters) had gone on to abuse. Peter (2006) concluded her discussion by reporting gender as a good conceptual tool to understand women's sex offending, however power is also important and may be quite useful.

Denov (2004) included the narratives of female victims of both male and female perpetrators. The female victims who were abused by their mother and father generally state that maternal sexual abuse was by far more damaging than paternal sexual abuse as the implied relationship of nurturer and caregiver in the mother-daughter relationship was shattered by the commission of abuse.

Female paedophilia online

Social media and online spaces have been adopted by paedophiles and other sexually predatory individuals to "legitimize, reinforce and facilitate their sexual interests in children" (Lambert & O'Halloran, 2008, p. 285). Elliot and Ashfield (2011) stated that female sex offenders on the Internet are much harder to detect than their male counterparts. This could be attributed to the small populations of female sex offenders. Another explanation relates to the anonymity of the Internet. As stated earlier, there is very little literature on female sex offenders and of that, very few articles related to female sex offenders online.

Clinical studies reveal that female sex offenders have difficulties with interpersonal relationships and the Internet may be a place for them to connect with others in a way that does not manifest the same threat as offline relationship building (Elliott & Ashfield, 2011; Lawson, 2008). In terms of a further research agenda to help understand female offending online, Elliot and Ashfield suggested the following three areas:

• how women use the Internet to fulfil a desire to connect with others;
• what role exposure to abusive material plays in manufacturing a desire to view more abusive material; and
• the effect of exposure to child pornography on attitudes towards children and sex (Elliott & Ashfield, 2011, p. 101).

The work of Lambert and O'Hallaran (2008) is of interest to this review as it echoes the work of Nathan and Ward (2002), mentioned above, concerning a more agentic conceptualisation of female sex offenders. Lambert and O'Halloran found a female paedophilia website and identified five women who posted on the site. A "deductive thematic analysis" of their narratives was undertaken and their exploratory findings suggest that female sex offenders are very much looking for sexual gratification in their interactions with children (Lambert & O'Halloran, 2008, p. 1). The women online were aware and made use of the connection between women and nurturing/mothering to conceal their offending under the guise of child care (Lambert & O'Halloran, 2008). The women's construction of male paedophiles as predatory and abusive contrasted strikingly with their construction of female paedophiles as the natural recipients of children's burgeoning sexuality. As reported in Lambert and O'Halloran (2008), in the Frequently Asked Questions section of the female paedophilia website the following passage appeared:

Adults do not have to awaken the sexuality of children in order for children to be sexual. Usually they do not. Children are sexual. (As cited in Lambert & O'Halloran, 2008, p. 291)

Lambert and O'Halloran (2008) found that in the personal narratives on the website there were "42 references to sexual motivation" (p. 289) for offending, and the authors concluded by saying that "one of the purposes of the present study was to establish the fact that deviant arousal patterns have a role in female sexual offending" (p. 297). It is worth consideration, particularly in terms of treatment interventions. However, this sample of women is extremely small and questions can be raised about the veracity of the posted comments on the website.

Limitations of studies on female sex offenders

There are many limitations regarding the findings concerning female sex offenders. The most pressing limitation is basically the lack of research on female sex offenders, types of sexual offences committed by women, and women's motivation to sexually offend. More research into all facets of female sexual offending would bring value to the field, including impacts on victims and prevention strategies.

Another limitation is that much of the literature featured in this review has relied on small samples. Small samples and small custodial populations indicate a very small population of female sex offenders. Small samples cannot be used to generalise about a population and only recently have efforts been made to replicate some of the studies. For example, Vandiver and Kercher (2004) suggested that small clinical samples on which typologies of female sex offenders have been based could lead to literature that incorrectly correlates mental illness with female sex offending. This can have an effect in how treatment is conceptualised.

The same issue applies to relying on known offenders in the criminal justice system. If research is based on women in the criminal justice system it will usually be the most serious sex offences that receive custodial sentences and will not be representative of the heterogeneity of female sexual offending/offenders.

Throughout the literature, sexual offences are also variously defined, leading to difficulty in comparing findings. Many of these issues plagued work on male sex offenders in the early phases - and still do.

A heavy reliance on gender stereotypes infiltrates dominant cultural understandings of female sex offending. If we can understand men's offending as multi-factorial, then it is possible to understand women's offending in the same way - highlighting gender as well as power, control, a history of abuse, coercion by a male partner, and other as yet uncovered motivations and underlying determinants.

A more complex and nuanced understanding based on more research would enable us to move away from the idea that sexual abuse by a woman is somehow less harmful than by a man. Certainly there is little evidence of this in the literature relating to impacts on victims.

Impact on victims

Child and adolescent victim/survivors

The literature regarding impacts on victims of female-perpetrated sexual abuse is predominately about child and adolescent victims. The following section outlines the short- and long-term impacts of child sexual abuse victimisation by a female offender.

Children who are victims of male- and female-perpetrated sexual abuse over a sustained period of time may display trauma symptoms because their psychological and emotional development is derailed from what would be considered to be the "normal" range (Herman, 1994). This is because they are forced to adjust to sometimes threatening and violent behaviour. This may still be the case when they do not quite understand the abuse or experience positive as well as negative feelings associated with the abuse. Positive feelings may be a result of nurturing behaviour on the part of the offender. The offender may make the child victim feel special or offer them attention that they find comforting (Knoll, 2010).

The impacts for victims of female-perpetrated sexual abuse appear to mirror those of male-perpetrated abuse (Deering & Mellor, 2011; Denov, 2004). However some variance is found relating to trust of women in later life and the sense of betrayal associated with a primary caregiver also being an abuser.

Gender

Impacts on victims of sexual abuse by a female offender are sometimes reported as being gendered, and this is certainly something important to explore (Angelides, 2010). Gendered impacts relate to a difference in how abuse is experienced when perpetrated by a male or a female, and the impacts will differ depending on whether the victim is male or female. As Kelly (1996) stated, "whilst no two experiences are the same, the meanings of abuse relate to gender, and impacts are also to some extent engendered" (p. 9).

Some accounts suggest that female-perpetrated abuse causes less harm to victims, in particular when the victim is male. In one case described by Deering and Mellor (2011) the young adolescent male victim made a statement that he was not negatively affected by what others were calling abuse. He had experienced the sexual contact with his teacher as positive and stated that he would only be negatively affected by it if the perpetrator was sentenced to prison. Denov (2004) countered this by arguing that male children and adults are often socialised to contain their emotional vulnerabilities and this would be particularly accurate if they suffered negative effects from being sexually assaulted or abused by a female offender.

Therefore the notion of "lack of harm" caused by female-perpetrated sexual assault relates to the subjective experience of victims as well as the perceived passive sexuality of women. Although it has been widely reported that female victims of male perpetrators suffer psychological and sometimes physical trauma at the time of the assault (followed by long- term effects), male victims of female perpetrators - particularly adolescent male victims - may experience physical pleasure at the time, but may experience trauma on a relational level after the abuse. This means that although at the time of the abuse the relationship with the female abuser may have felt equal, later on when the male victim understands the abuse of power, he may experience a sense of disempowerment and confusion over the relationship. This may be one of the reasons why some of the long-term impacts for male victim/survivors discussed below mirror those of female victim/survivors.

Deering and Mellor (2011) conducted an exploratory qualitative study of the self-reported impact of female-perpetrated childhood sexual abuse. For some men in this study there was a loss of masculine identity due to being victimised by a woman - the "weaker" sex. One participant described becoming "hyper-masculine" and over-sexualised with inexperienced young girls after the abuse to compensate for feelings of weakness. For female victims, a sense of betrayal characterises the effects of abuse by a female caregiver (Denov, 2004). As discussed above, close attention needs to be paid to the gendered expectations related to how victims respond to sexual abuse and assault.

Immediate and long-term impacts

For both male and female victim/survivors of female-perpetrated abuse some of the immediate impacts included feeling overwhelmed by emotions followed by guilt about being overwhelmed. Deering and Mellor (2011) described how victim/survivors experienced uncertainty and feelings of worthlessness around their peers. They also experienced symptoms of post-traumatic stress disorders such as intrusive flashbacks of the abuse. Other impacts experienced during the abuse and later in adolescence and adulthood include:

• depression;
• suicide ideation;
• extreme fear;
• anxiety; and
• inability to express emotion (Deering & Mellor, 2011).

Long-term impacts include:

• self-harming behaviours;
• sexual difficulties and dysfunctions;
• difficulty trusting others;
• feeling socially isolated;
• substance abuse; and
• rage (Deering & Mellor, 2011; Denov, 2004).

Specific to female-perpetrated sexual abuse, most of the participants in Deering and Mellor's (2011) study reported not being able to trust women and having difficulties in forming relationships with women. The authors concluded:

In the current study there was no evidence that males who experienced female-perpetrated child sexual abuse are less damaged or see the experience in positive terms, as has been suggested in previous research. (Deering & Mellor, 2011, p. 72)

Another impact of female-perpetrated abuse described in the literature relates to victims fearing they may also abuse their own children. In Denov's (2004) study one of the participants stated:

I know that my sexual stuff has really warped my ability to parent my daughter. I'm afraid to be alone with my daughter. It's probably one of the most troubling components of my adult life. You know, I'm good with her. But still, I'm afraid. I'm very afraid. It makes me spend less time with her than I think I normally would. (Jacob as quoted in Denov, 2004, p. 159)

Several of the participants in Denov's study described instances of sexual acting out, inappropriately touching others, and sexual fantasies related to violence toward women.

The impacts for victims of female-perpetrated sexual abuse seem to mirror those of male-perpetrated abuse. However some variance is found relating to trust of women in later life and the sense of betrayal associated with a primary caregiver also being an abuser.

Adult victim/survivors

There is very little research into the impacts of female sex offending on adult male and female victim/survivors. This section presents literature pertaining to sexual victimisation by a female as well as impacts of sexual abuse more broadly.

There is very little literature to draw from in relation to adult male victims of sexual assault by a female. One article by Fisher and Pina (2013) reported on the few studies conducted into male victims of female sexual abuse. It was found that the men in the study all reported the experience as traumatic and many viewed the act of sexual assault as "an act of aggression against them" (p. 56). Most of the literature on impacts for adult male victim/survivors relate to male-perpetrated sexual assault (see Du Mont, MacDonald, White, & Turner, 2013).

There is also very little literature to draw upon regarding the impacts on adult female victim/survivors of female-perpetrated sexual assault. The literature pertaining to impacts of sexual assault on female victim/survivors may be helpful, although is probably related to male-perpetrated assaults. Some of the impacts that female victim/survivors may experience, as described by Boyd (2011, pp. 2-6), include:

• psychological impacts - immediate and short term:
• anxiety and intense fear;
• ongoing fears related to the assault;
• fear of future attacks; and
• decreased self esteem;
• psychological impacts - medium to long term:
• self-blame, low self-esteem and guilt;
• denial;
• post-traumatic stress disorder;
• intrusive thoughts;
• hyper-arousal (sensitive response to stimuli); and
• avoidance;
• physical impacts;
• social and community impacts - relationships with family, friends and community affected by assault; and
• financial impacts - loss of earnings, medical costs, counselling expenses.

Due to the paucity of research into the impacts for victim/survivors of female-perpetrated abuse, particularly for adult victims, further research is required to inform therapeutic interventions for victim/survivors as well as increase awareness that female-perpetrated abuse does not necessarily cause less harm to its victims.

Disclosure

The literature on children trying to disclose female-perpetrated abuse to adults or authority figures - as with victims of male-perpetrated abuse - suggests that they are usually not believed. Denov (2004) described several instances where the perpetrator was alerted to the disclosure by the person/institution the victim/survivor disclosed to. These instances resulted in the child being physically punished by the perpetrator. Other narratives from the Deering and Mellor (2011) study indicated that in instances when young men who are abused by a female caregiver disclose to their peers, the abuse is minimised and treated as a consensual sexual encounter.

Denov (2004) believed that discomfort and lack of familiarity with the issue of female sex offenders affirms the "culture of denial" regarding female sex offenders (p. 163). One of Denov's participants, David, commented on his experience of disclosing to a mental health professional:

I felt very nervous but I thought, well, he's a psychologist, he should know what he's doing. When I told him about the sexual abuse [which occurred from age three to six], he didn't really seem to grasp it. I told him that some of the abuse I enjoyed and that's part of the guilt I was carrying … He said "I don't understand what your problem is … You don't have a problem". I don't think he saw [the sexual abuse] as a problem. I don't think he saw her as a perpetrator. (David as quoted in Denov, 2004, p. 165)

Peter (2008) reported participants from her study into mother-daughter sexual abuse found that disclosing mother-daughter abuse was a difficult and painful experience. Even those who disclosed to therapeutic counsellors were met with silence that served to deny their experiences and increase their distress. Other victim/survivors tried joining group therapy sessions for incest survivors and found the discussion was centred exclusively on male perpetrators.

Negative responses to abuse can have a devastating impact on victims who are seeking help, validation or support (Denov, 2004). We know from the literature on child and adult sexual abuse and assault that disclosing can be a very difficult process (Foster et al., 2012; Hunter, 2011; Stathopoulos, 2012; Wall, 2012). To have friends, family, police, or therapists disbelieve or minimise victim/survivors pain because the perpetrator is a woman only serves to isolate the victim/survivor, increase trauma symptoms, and reinforce their sense of loneliness. It also means that victims may never access the support they need in order to begin their healing process.

Treatment interventions for female sex offenders

Offender characteristics and offender motivations are a good starting point for beginning to conceptualise treatment options for female sex offenders. Similarly, social, emotional and mental disorders - which can often co-occur - also require intervention. However, little is known about the effectiveness of treatment interventions for female sex offenders as this population is so small, and there is very little empirical evidence regarding the efficacy of treatment.

Vandiver and Walker (2002) identified that most of the female sex offenders they studied displayed pro-social behaviours in other areas of their life. They suggested that female sex offenders would be much easier to engage in rehabilitative efforts than male sex offenders, who are often anti-social (less likely to follow social scripts or conform to social norms of behaviour) in more areas of their life. In a study by Vandiver (2006) concerning solo and co-offending female sex offenders, it was noted that when women offended on their own they tended to offend against male victims and when they offended with a co-offender (usually male) they tended to offend against female victims. Vandiver (2006) theorised that male and female sex offenders may have different motivations for offending and therefore different treatments would be required - treating male and female sex offenders (whether co-offenders or not) using similar treatment methods may not be therapeutic.

Lawson (2008) studied 20 records that had been compiled for the Sex Offender Screening and Risk Assessment program in the US, focusing on female sex offenders' relationship experiences. Three main categories were used in the thematic analysis of the records: personal perspective, intimate relationships, and social lives. Lawson (2008) found that the women had limited ability to meet their own social and emotional needs and this might be a key factor in any treatment interventions for female sex offenders. Lawson stated "specific attention should be paid to how these women address the everyday concerns that face all adults, so that they develop skills needed to engage in responsible sexual and social behaviour" (2008, p. 341). By enhancing the women's ability to lead pro-social lives, they may be equipped to make better choices.

In consideration of the findings in the offender characteristics table (Table 2), many female sex offenders have high rates of mental disorders - including depression, borderline personality disorder, and psychosis - as well as high levels of alcohol and drug abuse (Johansson-Love & Fremouw, 2009; Vandiver & Kercher, 2004; Wijkman et al., 2010, 2011). Similarly, there are high rates of child and adult sexual victimisation in the histories of female sex offenders (Johansson-Love & Fremouw, 2009; Nathan & Ward, 2002; Vandiver & Kercher, 2004; Wijkman et al., 2010). A child sexual abuse victimisation history may cause cognitive distortions about children and sexuality for sex offenders (Elliott & Ashfield, 2011). Mental disorders, substance abuse and child victimisation histories all require attention in any treatment interventions for female sex offenders.

Whether treatment is effective in reducing recidivism in female sex offenders, however, is not known because there is no empirical evidence on which to base such an assessment (Vess, 2011). In their study of officially recorded data and victimisation surveys on female sex offending in five countries, Cortoni et al. (2010) concluded that recidivism rates for female sex offending are extremely low. Using risk assessments based on male risk of sexual offence recidivism would only "overestimate the recidivism risk for female sex offenders", however there do not appear to be any viable alternatives at this time (p. 398). More research is required to develop risk assessment tools for female sex offenders which take into account the factors associated with female sexual offending recidivism.

A word on prevention

If there is very little literature on female sex offenders, there is even less on the prevention of female sex offending. Much of what is written concentrates on raising awareness rather than primary prevention (stopping abuse before it occurs). However there are also elements of secondary prevention, or what is often called intervention. Intervention is usually concerned with targeting education, information and support to at-risk communities.

Oliver (2007) suggested the following interventions as a first step in preventing female-perpetrated sexual abuse:

• Offering greater support to female victims of child sexual abuse - This is not to suggest that all females who are sexually abused as children will go on to abuse. However, a large number of detected female sex offenders do have a history of child sexual abuse and other forms of re-victimisation. Often the impacts of child sexual abuse can be severe and long lasting and can also lead women to abuse or neglect their children later in life (Cashmore & Shackel, 2013; Tarczon, 2012). Of course most women who are abused as children do not go on to abuse or neglect their children.
• Educating the public and human services professionals about female sex offenders - Targeted education toward police, legal actors, therapists, and primary health care professionals about the real impacts of female sex offending may lead to more compassionate and validating responses to victims (Denov, 2004; Oliver, 2007).

It is unlikely that due to the small number of female-perpetrated sexual offences committed by women, that there would be a great need for large scale prevention programs, however the shift toward prevention (rather than risk avoidance) in the field of child sexual abuse and adult sexual assault may be adequate in this space. Current prevention efforts concentrate of gender equality and respectful relationships and seek to empower children and adults alike.

Conclusion

Female sex offenders do not comfortably fit into the conceptual frameworks used to understand male sex offenders. This Research Summary has revealed that prevalence figures for female sex offending, although possibly an underestimation due to underreporting, are that females make up just under 5% of offenders (Cortoni & Hanson, 2005).⁴ This does not challenge the theory that sexual violence is a gendered crime, however it does pose a challenge in how to understand female sexual offending. Although many female sex offenders co-offend with male perpetrators, there exist a measure of women who are solo sexual offenders against children, adolescents, and adults. It is important to recognise the types of sexual abuse rather than to diminish them because they do not fit with the binary of male offender, female victim. This does not contradict our knowledge that the binary of male offender, female victim is by far the most prevalent form of sexual abuse and assault (ABS, 1996, 2006).

Recognising the harms that can be done by female sex offenders is important both culturally and legally. A belief that women cannot sexually offend has historically silenced victims and isolated them from the support they require to heal. At the same time, when female sex offenders are accepted as "real", their existence can sometimes be used to invalidate a gendered analysis of sexual abuse and sexual violence. That is, a case of a female sex offender can sometimes be used to deny that it is primarily men who commit sexual violence. This paper has presented evidence demonstrating female sex offenders are the exception that proves the rule that sexual violence is a crime predominately committed by men. The information contained in this Research Summary can be called upon to repudiate any claims that sexual violence is a crime committed equally by men and women.

By acknowledging female sexual offenders, system responses related to identification, treatment, and rehabilitation may begin to work towards further reducing those numbers and minimising harm to victims. Empirical data into the motivations of female sex offenders, their offending characteristics and behaviours can lead to a greater understanding of how to define typologies. Typologies can serve to assist the criminal justice system and clinicians to recognise victims and perpetrators and lead to better treatment for both. As the research indicates, many women who sexually offend are victims of child sexual abuse themselves. Kelly (1996) stated that "being victimized does not remove all responsibility, but it places actions and choices in a particular, constrained context" (p. 6). Attention to individuals who sexually abuse, be they male or female, cannot ignore the organisational and societal structures that condone and often silence sexual violence.

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