The key finding of this study is that disrupted parental bonding is associated with an increased level of adult psychopathic personality. Low maternal care was the key aspect of bonding most associated with psychopathy, while low paternal overprotection (i.e. increased autonomy and lack of regulatory control) was also important, especially in relation to the emotional detachment factor. Childhood physical abuse was also associated with psychopathy, but evidence from regression analyses suggests that bonding is more primary than abuse. Paternal bonding was of significance as it was associated with psychopathy after controlling for maternal care. These relationships remained significant after controlling for sex, social adversity and ethnicity. Prospective data on a small group suffering from significant bonding disruption in the first 3 years of life both confirmed links to later psychopathy and provided some validation of the self-report PBI. Findings indicate that maternal bonding and other psychosocial influences should not be ignored in the etiology of psychopathy, and for the first time implicate a role of bonding with the father.
Consistent with our hypothesis, low maternal care was the parental variable most strongly associated with both factors of adult psychopathy, reflecting the relatively greater impact of mothers. This finding is consistent with prior research showing that lack of maternal care was more consistently associated with adult psychopathology (including antisocial personality disorder) than paternal care (Enns et al. 2002
). Nevertheless, our study for the first time demonstrates a significant role of paternal bonding with respect to psychopathy. Low paternal overprotection was associated with higher scores on the emotional detachment factor of psychopathy, even after the effects of maternal care were accounted for. Low paternal overprotection scores reflect a lack of paternal involvement and regulatory control, and poor paternal monitoring and supervision. The significance of paternal bonding is consistent with prior work showing a trend for low paternal overprotection to be associated with increased risk for externalizing disorders (substance-use disorders and antisocial personality disorder) (Enns et al. 2002
). Similarly, low paternal involvement has been associated with the affective component of psychopathy (Farrington, 2006
). In addition, Wootton et al. (1997)
found that poor monitoring and supervision (within the context of a negative parenting composite) was related to greater callous-unemotional traits in 6-to 13-year-old youth. Lack of involvement and monitoring may impair the child’s capacity for bonding, and conversely the presence of a protective (albeit strict) father may enhance the emotional connection between father and child, conferring some protection from the development of affective features of psychopathy. Future studies on parental bonding taking both maternal and paternal bonding into account are warranted.
One of the strengths of the current study is that the prospective component confirmed the concurrent findings. The finding of significant associations between early separation from parents assessed at age 3 years and psychopathy scores at age 28 years lends preliminary prospective support to the hypothesis that poor bonding predisposes to psychopathy, particularly the deviant behavior feature. This is broadly consistent with the finding that parental separation prior to age 10 years predicted the antisocial component of adult psychopathy but not the affective component (Farrington, 2006
). The fact that children separated from parents in the first 3 years of life showed significantly lower bonding scores in adulthood also shows some construct validity for the PBI and lends more credence to the concurrent relationships that we observed at age 28 years. Interestingly, children separated from their parents in the early years showed significantly lower maternal care scores and a trend (p
<0.08) for reduced parental overprotection, the two components of bonding that related to psychopathy. This convergence of findings implicates these specific forms of maternal and paternal bonding in particular, rather than global bonding impairments in general.
Parental bonding was associated with both factors of psychopathy whereas abuse was only related to the deviant behavior factor. Furthermore, a significant abuse×maternal care interaction was observed, suggesting that parental bonding (especially lack of maternal care) may be a relatively more potent process than abuse in shaping psychopathic personality, given that it increases psychopathy scores in both conditions (i.e. whether abuse is present or not), and given the prior emphasis placed on lack of maternal care in predisposing to psychopathy (Bowlby, 1969
; Rutter, 1982
). Because this interaction could be a chance finding, future studies assessing both abuse and bonding are needed to replicate and extend this interaction effect. Nevertheless, the differential associations between bonding and psychopathy subfactors are broadly consistent with prior psychosocial research (Harpur et al. 1989
; Hare, 2003
). Seminal theories of primary and secondary psychopathy (Karpman, 1948
; Porter, 1996
) argue that primary psychopathy (i.e. the emotional detachment factor) is more influenced by genetics while secondary psychopathy (i.e. the deviant behavior factor) is more environmentally influenced (abuse and bonding). Our findings in contrast suggest that abuse and bonding may have somewhat differential influences on psychopathy.
Findings may have prevention and intervention implications. Programs aimed at strengthening parental bonding, improving the quality of parenting and reducing physical abuse may be especially helpful. One longitudinal study of pregnant mothers randomized to a home visit program aimed at promoting maternal care and functioning demonstrated significantly lower scores on child abuse and neglect as well as juvenile delinquency 15 years later (Olds et al. 1997
). We nevertheless caution that common genetic influences could account for both the poor bonding in the parent and also the psychopathic personality in the offspring. Twin studies that include bonding and psychopathy measures are required to tease out the effects of genetic influences on the bonding–psychopathy relationship.
An unanswered question concerns the mechanism of action underlying the association between parental bonding and psychopathic personality. According to attachment theory, individuals who are not emotionally bonded or attached to warm and caring parents tend to become antisocial (Bowlby, 1969
; Carlson & Sroufe, 1995
). Neurobiologically, parental deprivation or parental loss may induce enduring changes in neuroendocrine functioning, specifically alterations of hypothalamic–pituitary–adrenal (HPA) axis function. Early maternal deprivation reduces central nervous system serotonin turnover in Rhesus infant monkeys (Shannon et al. 2005
). Parental desertion and very low levels of care have been associated with abnormal cortisol levels and stress responses in humans (Luecken, 2000
; Kertes et al. 2008
; Tyrka et al. 2008
). Abnormal HPA axis functioning has been associated with psychopathic traits in prisoners (Cima et al. 2008
) and with callous-unemotional traits in community adolescents (Loney et al. 2005
). Therefore, it is possible that early parental deprivation predisposes to later development of psychopathic traits by altering HPA axis functioning.
Finally, limitations of this study should be recognized. This community sample is culturally and ethnically unique, so the findings may not necessarily generalize to Western samples or to clinical populations. In addition, due caution should be exercised in interpreting the effects for the emotional detachment subfactor of psychopathy, given that its association with bonding was only observed in retrospective but not prospective data. As with many prior studies, we used self-report measures of bonding, abuse and psychopathic personality which have their limitations. Later functioning at age 28 years could affect retrospective memories and reports of individuals’ bonding to parents and even of reports of childhood physical abuse. We made efforts to address this limitation by using computerized data collection procedures to maximize openness/honesty, and by using a prospective, longitudinal design to validate the self-report measure on bonding. Although the sample size of children separated from their parents in this prospective study component was small, this longitudinal sample confirms that disruption to early bonding predisposes to psychopathy, despite lack of statistical power. Furthermore, small sample size biases towards type II rather than type I errors. Similarly, the relatively low internal consistency of the SRP-II in the current sample may have underestimated psychosocial–psychopathic personality associations. Nevertheless, findings are suggestive of possible links between bonding and psychopathy, and future longitudinal studies with large sample size are needed to replicate the current findings. Another limitation consists of self-report psychopathy as opposed to use of the PCL-R, the most widely used assessment tool of psychopathy, specifically in correctional settings (Hare, 2003
). We were constrained in this context by the use of a non-institutionalized community sample, although we did utilize an instrument developed by Hare (1991b)
which has been validated against PCL-R ratings in prisoners (Hare, 1991a
). We were also unable to collect other abuse other than physical abuse data from the current sample. Finally, it is possible that a third evocative factor, such as personality and temperamental traits in the child that predispose to adult psychopathic personality, may elicit low levels of care or overprotection from the parents. Furthermore, the six preschool children separated from both of their parents by age 3 years may have been at higher risk for later foster care, which may partly account for the association between poor bonding/abuse and psychopathic personality. Despite these limitations, it is felt that this study helps address an important, decades-old gap in the literature on bonding and psychopathy. Converging findings from prospective and concurrent study designs draw attention to the potential critical importance of specific components of bonding in predisposing to adult psychopathy, highlight the neglected role of paternal bonding, and have potential implications for early intervention and prevention of psychopathy. Given the critical role of the early psychosocial environment on brain development, and given brain influences on psychopathy (Raine & Yang, 2006
), it is felt that future neurobiological research on psychopathy could be potentiated by the inclusion of parental bonding measures.