Eric J. Connolly

DEMONSTRATING THE VALIDITY OF TWIN RESEARCH IN CRIMINOLOGY

In a recent article published in Criminology, Burt and Simons (2014) claimed that the statistical violations of the classical twin design render heritability studies useless. Claiming quantitative genetics is “fatally flawed” and describing the results generated from these models as “preposterous,” Burt and Simons took the unprecedented step to call for abandoning heritability studies and their constituent findings. We show that their call for an “end to heritability studies” was premature, misleading, and entirely without merit. Specifically, we trace the history of behavioral genetics and show that 1) the Burt and Simons critique dates back 40 years and has been subject to a broad array of empirical investigations, 2) the violation of assumptions in twin models does not invalidate their results, and 3) Burt and Simons created a distorted and highly misleading portrait of behavioral genetics and those who use quantitative genetic approaches. “The flaws of twin studies are not fatal, but rather seem no worse (and may be better) than the flaws of the typical causal study that relies on observational data.” (Felson, 2012: ii)

Examining the Genetic and Environmental Influences on Self-Control and Delinquency Results From a Genetically Informative Analysis of Sibling Pairs

The Child and Young Adult Supplement of the National Longitudinal Survey of Youth (CNLSY) has been used extensively within criminology. A significant amount of criminological research, for example, has explored various issues related to the correlates, causes, and consequences associated with levels of self-control and delinquent involvement. The overwhelming majority of these CNLSY studies, however, have not accounted for the potential effects of genetic factors on these two widely studied criminological variables and thus the findings generated from previous empirical work may be inaccurate due to genetic confounding. The current study partially addresses this possibility by analyzing a sample of kinship pairs nested within the CNLSY. Analyses of these data revealed that genetic factors accounted for between 51% and 92% of the variance in levels of self-control and between 30% and 41% of the variance in delinquency. We discuss the implications of these results for interpreting findings from the large body of existing research using the CNLSY.

MATHEMATICAL PROOF IS NOT MINUTIAE AND IRREDUCIBLE COMPLEXITY IS NOT A THEORY: A FINAL RESPONSE TO BURT AND SIMONS AND A CALL TO CRIMINOLOGISTS†

KEYWORDS: biosocial, assumptions, twinsIn their initial article, Burt and Simons (2014) laid out a range of specific criticismsof twin-based research. They argued that violations of the statistical assumptions thatunderpin this line of work result in upwardly biased estimates of heritability and down-wardlybiasedestimatesofenvironmentaleffects.AccordingtoBurtandSimons,thefind-ingsgeneratedfrombehavioralgeneticapproachesare“biologicallynonsensical”andare“misguided.” Indeed, Burt and Simons stated, without qualification, that an entire classof statistical models used to analyze twin data are “seriously flawed.” Because behavioralgenetic designs suffer from “fatal flaws,” they argued, twin-based research designs andtheir associated statistical methods should be put to an “end in criminology.”We examined their assertions carefully. We found that Burt and Simons (2014) cherry-picked the studies they cited in support of their position regarding the biasing impact ofthe equal environments assumption (EEA), something they openly admit in the onlinesupporting information of their rejoinder (Burt and Simons, 2015, this issue). Specifically,theystate,“wefocusedonarticlesthatshowedthattheEEAisnotavalidassumption”tosupport their claim that heritability estimates from behavioral genetic studies are chron-ically overestimated as a result of violations of this assumption. In fact, they relied pri-marily on a single source (Joseph, 1998, 2004, 2006, 2010) for their critique. Notably, wefound that they failed to cite the vast majority of the more than 60 studies that tested forviolations of the EEA—a body of work that is inconsistent with their claims.

Considering the Genetic and Environmental Overlap Between Bullying Victimization, Delinquency, and Symptoms of Depression/Anxiety

Emerging evidence from longitudinal research suggests that bullied children are more likely to develop antisocial tendencies and mental health problems later in life. Less research, however, has used genetically sensitive research designs to control for genetic confounding and examine whether the well-supported association between bullying victimization and maladaptive development is partially accounted for by common genetic and environmental influences. Using sibling data from the National Longitudinal Survey of Youth 1997, the current study used a series of bivariate liability-threshold models to disentangle the genetic and environmental influences on observed covariance between repeated bullying victimization, delinquent involvement, and symptoms of depression/anxiety. Results revealed that common additive genetic and nonshared environmental effects accounted for the covariance in liability between bullying victimization and delinquent involvement as well as bullying victimization and symptoms of depression/anxiety. The results suggest the presence of genotype–environment correlation (rGE) between repeated victimization and maladaptive development.

Psychopathic personality traits and their influence on parenting quality: results from a nationally representative sample of Americans.

Psychopathic personality traits have consistently been found to predict a range of negative and dysfunctional outcomes. As a result, it is somewhat surprising that the research to date has failed to empirically examine the potential association between psychopathic personality traits and parenting quality. The current study addressed this omission in the literature by analyzing a community sample of adults. The results revealed that respondents scoring higher on psychopathic personality traits tended to report more negative parenting quality. These results were detected for both males and females and remained significant even after controlling for the effects of parental transmission and child-effects. To our knowledge, this is the first study to show a statistically significant association between psychopathic personality traits and parenting quality. We conclude with a discussion of what these findings mean for psychopathy research and the parenting the literature.

Head Injuries and Changes in Delinquency from Adolescence to Emerging Adulthood: The Importance of Self-control as a Mediating Influence

Objectives: The current study examines whether head injuries suffered earlier in the life course are associated with subsequent changes in self-control and delinquency. Methods: Latent growth curve models and path analysis are used to analyze the developmental trajectories of self-control and delinquency as well as the potential associations between head injury, self-control, and delinquency among a sample of youth offenders from the pathways to desistance study. Results: The results revealed significant associations between head injuries and short-term changes in self-control and subsequent increases in aggressive delinquency. Indirect pathway models revealed that lower levels of self-control significantly mediated the association between head injuries and starting levels in aggressive delinquency. The association between head injuries and changes in aggressive delinquency was also significantly mediated by self-control, but the association was negative, indicating that youth who previously suffered head injuries desisted from aggressive delinquency at a slightly faster rate than their noninjured peers. Additional analyses revealed that, despite accelerated rates of decline, injured youth engaged in significantly higher levels of aggressive delinquency throughout the entire observation period. Conclusion: Head injuries represent one environmental factor that may influence delinquent behaviors through their influence on biological and developmental processes.

Sex Differences in Childhood Bullying Victimization and Trajectories of Substance Use From Adolescence to Adulthood

Recent research has found that repeated bullying victimization increases the risk of developing several unhealthy habits later in life including periodic substance use. Comparatively less research, however, has examined whether the association between bullying victimization and developmental growth in substance use is different for males and females. The present study addressed this gap in the literature by analyzing data from the National Longitudinal Survey of Youth 1997. Results from a series of sex-specific latent growth curve models reveal that bullied males experience faster increases in cigarette and marijuana use from adolescence to young adulthood compared to non-bullied males, while bullied females experience faster increases in cigarette use compared to non-bullied females. Bullied males also experience slower declines in cigarette and marijuana use from adolescence to middle adulthood, while bullied females experience slower declines in alcohol and cigarette use. Implications of these findings for research on sex differences in bullying victimization and developmental patterns of substance use are discussed.

Identifying Latent Classes of Antisocial Behavior Among Youth From Saudi Arabia An Assessment of the Co-Occurrence Between Aggression, Psychopathy, Low Self-Control, and Delinquent Behavior

Despite the wealth of knowledge on subclass formation for antisocial behavior among youth from the United States and other Western industrialized countries, very little is known about the subclass structure for antisocial behavior among youth growing up in other geographical contexts. Using validated measures of aggression, psychopathy, and low self-control, we employ latent class analysis to identify latent subgroups of antisocial behavior from a sample of 324 Saudi Arabian youth. Three classes of antisocial behavior emerged and significant associations between latent class membership and different forms of delinquency were observed. The findings are the first to show a similar pattern of latent class formation for antisocial behavior and risk for violent and nonviolent delinquency among Saudi Arabian youth compared to U.S. youth.

Guns, Gangs, and Genes: Evidence of an Underlying Genetic Influence on Gang Involvement and Carrying a Handgun

Handgun and gang violence represent two important threats to public safety. Although several studies have examined the factors that increase the risk for gang membership and handgun carrying, few studies have explored the biosocial underpinnings to the development of both gang involvement and carrying a handgun. The current study addressed this gap in the literature by using kinship data from the National Longitudinal Survey of Youth 1997 to estimate the genetic and environmental effects on gang membership, handgun carrying, and the covariance between the two. Results revealed that genetic and nonshared environmental influences accounted for much of the association between gang membership and handgun carrying. Implications of these findings for future gang research are discussed.

Genetic and Environmental Influences on the Development of Childhood Antisocial Behavior: Current Evidence and Directions for Future Research

During the past couple of decades, there has been a tremendous amount of empirical research examining the genetic foundation to antisocial behaviors at various stages of the life course. The results of these studies have consistently revealed that about 50% of the variance in antisocial behaviors is the result of genetic factors, with most of the remaining variance being attributable to nonshared environmental influences. More recently, there has been a significant focus on trying to identify the specific genes that might be involved in the etiology of these types of behaviors. Although the findings have been relatively inconsistent and mixed, there is an emerging body of research indicating that genes have their most consistent and powerful effects when they are paired to environmental risk factors. Unfortunately, most of this genetic research has yet to be integrated into life-course criminology. The purpose of the current chapter is to review some of the research bearing on the genetic underpinnings to antisocial behaviors and discuss the various ways that it has application to criminological theory and research and to offer avenues for future research.