Environmental transmission of violent criminal behavior in siblings: a Swedish national study

Using age difference and sex similarity to detect evidence of sibling influence on criminal offending

BACKGROUND

Sibling resemblance in crime may be due to genetic relatedness, shared environment, and/or the interpersonal influence of siblings on each other. This latter process can be understood as a type of 'peer effect' in that it is based on social learning between individuals occupying the same status in the social system (family). Building on prior research, we hypothesized that sibling pairs that resemble peer relationships the most, i.e., same-sex siblings close in age, exhibit the most sibling resemblance in crime.

METHODS

Drawing on administrative microdata covering Finnish children born in 1985-97, we examined 213 911 sibling pairs, observing the recorded criminality of each sibling between ages 11 and 20. We estimated multivariate regression models controlling for individual and family characteristics, and employed fixed-effects models to analyze the temporal co-occurrence of sibling delinquency.

RESULTS

Among younger siblings with a criminal older sibling, the adjusted prevalence estimates of criminal offending decreased from 32 to 25% as the age differences increased from less than 13 months to 25-28 months. The prevalence leveled off at 23% when age difference reached 37-40 months or more. These effects were statistically significant only among same-sex sibling pairs (p < 0.001), with clear evidence of contemporaneous offending among siblings with minimal age difference.

CONCLUSIONS

Same-sex siblings very close in age stand out as having the highest sibling resemblance in crime. This finding suggests that a meaningful share of sibling similarity in criminal offending is due to a process akin to peer influence, typically flowing from the older to the younger sibling.

The Sibling Effect for Delinquency: Mediation by Proactive Criminal Thinking and Moderation by Age

This study tested whether the sibling delinquency effect, like the peer influence effect, is mediated by proactive (planned, calculated, and amoral) criminal thinking. Youth who completed the Offending, Crime and Justice Survey (OCJS) and had a sibling living at home were divided into an early adolescent subsample (n = 795) and a mid-adolescent subsample (n = 532) after it was determined that age moderated the effect of sibling delinquency on proactive criminal thinking and serious offending. The results of a causal mediation analysis revealed a significant pathway running from sibling delinquency at Wave 1, to proactive criminal thinking at Wave 2, to serious offending at Wave 3, but only in the early adolescent subsample. These results suggest that the sibling delinquency effect may be the result of learning proactive criminal thinking in association with a delinquent sibling while still an early adolescent.

Are There Early Risk Markers for Pedophilia? A Nationwide Case-Control Study of Child Sexual Exploitation Material Offenders

Although prior research suggests associations between parental characteristics and later sexual offending in offspring, possible links between early pregnancy-related factors and sexual offending remain unclear. Early risk markers unique to sexual offending, however, may be more prominent among sexual offenders with atypical sexual interests, such as individuals involved with child sexual exploitation material (CSEM; also referred to as child pornography). We examined the prospective association between parental and pregnancy-related risk markers and a behavioral indicator of pedophilic interest, CSEM offending. All 655 men born in Sweden and convicted of CSEM offending between 1988 to 2009 were matched 1:5 on sex, birth year, and county of birth in Sweden to 3,928 controls without sexual or nonsexual violent convictions. Paternal age (adjusted odds ratio [AOR] = 1.3, 95% confidence interval [CI] [1.1, 1.7]), parental education (AOR = 0.8, 95% CI [0.6, 0.9]), parental violent criminality (AOR = 2.9, 95% CI [2.2, 3.8]), number of older brothers (AOR = 0.8, 95% CI [0.6, 0.9] per brother), and congenital malformations (AOR = 1.7, 95% CI [1.2, 2.4]) all independently predicted CSEM convictions. This large-scale, nationwide study suggests parental risk markers for CSEM offending. We did not, however, find convincing evidence for pregnancy-related risk markers, with the exception of congenital malformations and having fewer older brothers.

Evaluation of a multi-site program designed to strengthen relational bonds for siblings separated by foster care

Sibling relationships in foster care settings have received increased attention in recent years. Despite growing evidence regarding the protective potential of sibling relationships for youth in care, some sibling groups continue to experience foster care related separation, and few programs exist to address the needs of these youth. This study describes and evaluates Camp To Belong, a multi-site program designed to provide short-term reunification to separated sibling groups through a week-long summer camp experience. Using a pre-test post-test survey design, this paper examines changes in youth ratings of sibling conflict and sibling support across camps located in six geographically distinct regions of the United States. The effects of youth age, number of prior camp exposures, and camp location were tested using multilevel modeling procedures. Findings suggest that participation in Camp To Belong may reduce sibling conflict, and improvements in sibling support are noted for youth who have had prior exposure to the camp's programming. Camp-level variance in the sibling support outcome highlight the complex nature of relationships for siblings separated by foster care, and suggest the need for additional research. Lessons learned from this multi-site evaluation and future directions are discussed.

And What About Siblings? A Longitudinal Analysis of Sibling Effects on Youth's Intergroup Attitudes

Within the process of political socialization, the family is of particular importance. Apart from parents, however, little is known about the role of other close family members. The present study examined if siblings affect each other's intergroup attitudes (i.e., intolerance towards immigrants, social dominance orientation). Drawing on a sample of 362 sibling dyads (older siblings: M _age = 17.77, 53.6% female; younger siblings: M _age = 13.61, 61.3% female), the results showed that older siblings' intergroup attitudes predicted younger siblings' attitudes, but this effect was moderated by gender. Specifically, older siblings' intolerance and social dominance orientation were only found to affect their younger sisters, yet not their younger brothers. Although younger siblings' intergroup attitudes had no main effect on older siblings, a significant moderation by age indicated that younger siblings affected older siblings' social dominance orientation with increasing age. These moderation effects of age and gender were not mediated by the quality of family relationships. The findings also remained the same when parental intergroup attitudes were taken into account. While siblings were generally identified as an important agent of political socialization in youth, the results also highlight the necessity to further examine the mechanism that either facilitate or hinder sibling effects.

The Decomposition of Shared Environmental Influences on Externalizing Syndromes in the Swedish Population: A Multivariate Study

Using information from Swedish population registries, we attempt to decompose the shared environment (C) into four subcomponents: close family, family, household, and community. Among pairs differing in their genetic and geographical/household relationships, we examine three externalizing syndromes: drug abuse (DA), criminal behavior (CB), and alcohol use disorders (AUD). The best-fitting common pathway model suggested that total estimates for C were higher for DA (21% for males and 18% for females) than for AUD (16% and 14%) and CB (17% and 10%). Concerning syndrome-specific influences in males, close family effects were stronger for CB and AUD, while community effects were stronger for DA. The two C components in between community experiences and close family experiences (family and household) were estimated to almost entirely derive from the common latent factor. In females, among the four components of C, the community experiences were just slightly above zero, while the C components referred to as the household effect were almost zero. The total close family experiences were similar and most important across syndromes were also divided into common and specific components. For all syndromes, for both males and females, the effects of additive genetic factors were 2-4 times the size of the total effect of the shared environment. Applying standard methods to novel relationships, we expand our understanding of how the shared environment contributes to individual differences in three externalizing syndromes.

Parental and perinatal risk factors for sexual offending in men: a nationwide case-control study

BACKGROUND

Prior studies suggest parental and perinatal risk factors are associated with later offending. It remains uncertain, however, if such risk factors are similarly related to sexual offending.

METHOD

We linked socio-demographic, family relations, and perinatal (obtained at birth) data from the nationwide Swedish registers from 1973 to 2009 with information on criminal convictions of cases and control subjects. Male sex offenders (n = 13 773) were matched 1:5 on birth year and county of birth in Sweden to male controls without sexual or non-sexual violent convictions. To examine risk-factor specificity for sexual offending, we also compared male violent, non-sexual offenders (n = 135 953) to controls without sexual or non-sexual violent convictions. Predictors included parental (young maternal or paternal age at son's birth, educational attainment, violent crime, psychiatric disorder, substance misuse, suicide attempt) and perinatal (number of older brothers, low Apgar score, low birth weight, being small for gestational age, congenital malformations, small head size) variables.

RESULTS

Conditional logistic regression models found consistent patterns of statistically significant, small to moderate independent associations of parental risk factors with sons' sexual offending and non-sexual violent offending. For perinatal risk factors, patterns varied more; small for gestational age and small head size exhibited similar risk effects for both offence types whereas a higher number of older biological brothers and any congenital malformation were small, independent risk factors only for non-sexual violence.

CONCLUSIONS

This nationwide study suggests substantial commonalities in parental and perinatal risk factors for the onset of sexual and non-sexual violent offending.

A novel sibling-based design to quantify genetic and shared environmental effects: application to drug abuse, alcohol use disorder and criminal behavior

BACKGROUND

Twin studies have been criticized for upwardly biased estimates that might contribute to the missing heritability problem.

METHOD

We identified, from the general Swedish population born 1960-1990, informative sibships containing a proband, one reared-together full- or half-sibling and a full-, step- or half-sibling with varying degrees of childhood cohabitation with the proband. Estimates of genetic, shared and individual specific environment for drug abuse (DA), alcohol use disorder (AUD) and criminal behavior (CB), assessed from medical, legal or pharmacy registries, were obtained using Mplus.

RESULTS

Aggregate estimates of additive genetic effects for DA, AUD and CB obtained separately in males and females varied from 0.46 to 0.73 and agreed with those obtained from monozygotic and dizygotic twins from the same population. Of 54 heritability estimates from individual classes of informative sibling trios (3 syndromes × 9 classes of trios × 2 sexes), heritability estimates from the siblings were lower, tied and higher than those from obtained from twins in 26, one and 27 comparisons, respectively. By contrast, of 54 shared environmental estimates, 33 were lower than those found in twins, one tied and 20 were higher.

CONCLUSIONS

With adequate information, human populations can provide many methods for estimating genetic and shared environmental effects. For the three externalizing syndromes examined, concerns that heritability estimates from twin studies are upwardly biased or were not generalizable to more typical kinds of siblings were not supported. Overestimation of heritability from twin studies is not a likely explanation for the missing heritability problem.

The etiologic role of genetic and environmental factors in criminal behavior as determined from full- and half-sibling pairs: an evaluation of the validity of the twin method

BACKGROUND

Twin studies have shown that criminal behavior (CB) is influenced by both genetic and shared environmental factors. Could these results be replicated using full-siblings and half-siblings?

METHOD

In 911 009 full-siblings reared together (FSRT), 41 872 half-siblings reared together (HSRT) and 52 590 half-siblings reared apart (HSRA), CB was assessed from the Swedish Crime Register. Modeling, including testing for age differences and rearing status, was performed using the OpenMx package.

RESULTS

Five sibling models were fitted examining FSRT and HSRT 0-2 years different in age, and both FSRT and HSRT, and FSRT, HSRT and HSRA 0-10 years different in age with and without a specified shared environment indexing age differences. Heritability estimates for CB ranged from 33 to 55% in females and 39 to 56% in males, similar to those found in our prior twin study on the same population. Estimates for the shared environment varied from 1 to 14% in females and 10 to 23% in males, lower than those estimated in the twin study. The specified shared environment indexed by sibling age differences was significant in all models tested.

CONCLUSIONS

Heritability estimates for CB from full- and half-siblings closely approximated those found from twins in the same population, validating the twin method. Shared environmental estimates were lower, suggesting the presence of shared environmental factors for CB specific to twins. When rearing status can be assessed, full- and half-siblings offer an additional method for assessing the role of genetic and environmental factors in complex disorders. However, age differences in siblings may need to be included in the models.