Behavioral Genetic Studies Research Articles

Editorial: Answering questions in developmental science: separating the wheat from the chaff

Editorial: Answering questions in developmental science: separating the wheat from the chaff

Novel repeat polymorphisms of the dopaminergic neurotransmitter genes among dogs and wolves

Genetic polymorphisms of the neurotransmission systems are intensively studied in the human because of a possible influence on personality traits and the risk of psychiatric disorders. The investigation of genetic variations of the dog genome has recently been a promising approach, as a considerable similarity can be observed between dogs and humans, in both genetic and social aspects, suggesting that the dog could become an appropriate animal model of human behavioral genetic studies. The aim of our study was the identification and analysis of variable number of tandem repeats polymorphisms (VNTRs) in the genes of the dopaminergic neurotransmitter system of dogs. The in silico search was followed by the development of PCR-based techniques for the analysis of the putative VNTRs. Highly variable repetitive sequence regions were found in the tyrosine hydroxylase (TH), dopamine transporter (DAT), and dopamine beta-hydroxylase (DBH) genes. Allele frequency and genotype distribution of these novel polymorphisms together with the exon 3 and exon 1 VNTR of the dopamine D4 receptor gene were determined in a large sample involving four dog breeds (German Shepherd, Belgian Tervueren, Groenandael, and Malinois) and European Grey Wolves. A significant difference of allele and genotype frequencies was demonstrated among the analyzed breeds; therefore, an association analysis was also carried out between the activity-impulsivity phenotype and the described VNTRs. Preliminary findings are presented that polymorphisms of the DRD4, DBH, and DAT genes can be associated with attention deficit among Belgian Tervuerens.

Season of Birth and Dopamine Receptor Gene Associations with Impulsivity, Sensation Seeking and Reproductive Behaviors

BackgroundSeason of birth (SOB) has been associated with many physiological and psychological traits including novelty seeking and sensation seeking. Similar traits have been associated with genetic polymorphisms in the dopamine system. SOB and dopamine receptor genetic polymorphisms may independently and interactively influence similar behaviors through their common effects on the dopaminergic system.Methodology/Principal FindingsBased on a sample of 195 subjects, we examined whether SOB was associated with impulsivity, sensation seeking and reproductive behaviors. Additionally we examined potential interactions of dopamine receptor genes with SOB for the same set of traits. Phenotypes were evaluated using the Sociosexual Orientation Inventory, the Barratt Impulsivity Scale, the Eysenck Impulsivity Questionnaire, the Sensation Seeking Scale, and the Delay Discounting Task. Subjects were also asked about their age at first sex as well as their desired age at the birth of their first child. The dopamine gene polymorphisms examined were Dopamine Receptor D2 (DRD2) TaqI A and D4 (DRD4) 48 bp VNTR. Primary analyses included factorial gender×SOB ANOVAs or binary logistic regression models for each dependent trait. Secondary analysis extended the factorial models by also including DRD2 and DRD4 genotypes as independent variables. Winter-born males were more sensation seeking than non-winter born males. In factorial models including both genotype and season of birth as variables, two previously unobserved effects were discovered: (1) a SOB×DRD4 interaction effect on venturesomeness and (2) a DRD2×DRD4 interaction effect on sensation seeking.ConclusionThese results are consistent with past findings that SOB is related to sensation seeking. Additionally, these results provide tentative support for the hypothesis that SOB modifies the behavioral expression of dopaminergic genetic polymorphism. These findings suggest that SOB should be included in future studies of risky behaviors and behavioral genetic studies of the dopamine system.

Premature and Delayed Ejaculation: Genetic and Environmental Effects in a Population-Based Sample of Finnish Twins

A number of different theoretical approaches to understanding the etiology of ejaculatory dysfunction have been proposed, but no behavior genetic study has yet, to our knowledge, been conducted to explore the genetic and environmental influences on ejaculatory dysfunction. The aim of the present study was to explore the genetic and environmental effects on premature (PE) and delayed (DE) ejaculation in a population-based sample. The genetic and environmental influences on PE and DE were investigated in a population-based sample of 1,196 Finnish male twins, age 33-43 years, with 91 identical and 110 complete twin pairs. Several different aspects of ejaculatory function were measured by a self-report questionnaire (e.g., latency time, subjective experience of ejaculatory control). Factor analyses distinguished two subcomponents of ejaculatory function, and subsequently, composite variables measuring PE and DE were created. Structural equation modeling was performed on the composite variables. Measurement of genetic and environmental effects on PE and DE. The results suggested moderate genetic influence (28%) on PE, but not on DE (0%). There was a moderate familial effect on DE with shared environmental effects accounting for 24% of the variance. However, omission of the shared environmental component did not directly result in a significantly decreased model fit for DE, and omission of the additive genetic component did not directly result in a significantly decreased fit for the PE model. The findings from the present study provide useful information regarding the etiology and understanding of ejaculatory dysfunction.

Evolutionary psychology and genetic variation: non-adaptive, fitness-related and adaptive.

Behavioural variation across individuals can be substantial. A broad generalization emerging from three decades of behavioural genetic studies is that most psychological individual differences have moderate broad heritabilities (30-60%). There are at least three possible scenarios for this genetic variation. First, it may be adaptively neutral and not subject to selection. Second, it may be related to fitness despite selection. Third, it may be maintained by selection for alternative adaptations. Some authors favour the first of these possibilities, but the latter two cannot be ruled out. First, temporally varying selection pressures (e.g. pathogens) can maintain fitness-related genetic variance in a population despite current selection pressures. Moreover, direct and indirect evidence on humans support the notion that some phenotypic variance is fitness related. Second, while adaptive alternatives are unlikely to be found at a level of highly complex design, frequency dependent selection can maintain variation at finer, quantitative levels. One potential example is discussed. Because of their particular relevance to evolutionary psychology, fitness-related and adaptive genetic variance deserve further attention.

Behavioral genetics and taste.

This review focuses on behavioral genetic studies of sweet, umami, bitter and salt taste responses in mammals. Studies involving mouse inbred strain comparisons and genetic analyses, and their impact on elucidation of taste receptors and transduction mechanisms are discussed. Finally, the effect of genetic variation in taste responsiveness on complex traits such as drug intake is considered. Recent advances in development of genomic resources make behavioral genetics a powerful approach for understanding mechanisms of taste.

Continuity and change in behavioral inhibition and activation systems: A longitudinal behavioral genetic study

Although there is a great deal of interest in the Behavioral Inhibition System (BIS) and Behavioral Activation System (BAS)—two temperaments formulated by Gray’s reinforcement sensitivity theory—few studies have examined the genetic and environmental etiology underlying their continuity and change. Using a two-wave longitudinal data set of twins from late adolescence to early adulthood, this study examined (1) whether genetic influences contribute to change as well as continuity of the two temperaments and (2) whether the magnitude of genetic influences on the BIS and BAS differs across the two measurement points. The questionnaire was administered to 448 twin pairs at two waves, with an interval of approximately 2–3 years. Univariate genetic analyses revealed that genetic factors accounted for around one-third of the phenotypic variance in the BIS and BAS traits at both waves. Longitudinal bivariate analyses revealed that (1) genetic influences contribute only to continuity, whereas environmental influences contribute to both continuity and change in the two traits, and (2) the degree of genetic influences does not differ across time. These results suggest that in this age period, temporal stability of individual differences in the BIS and BAS owes more to genetic than to environmental factors.

The Undertheorized Environment: Sociological Theory and the Ontology of Behavioral Genetics

Growing interest in the genetic contribution to human behaviors has led to the growth of the field of behavioral genetics. The authors consider the concept of “environment” in behavioral genetics and argue that sociology is in a unique position to evaluate and specify a theoretically robust concept of environment. Building on insights from classical and contemporary social theory, the authors argue that the study of genetic influence on behavior needs to incorporate sociological understandings of contextual effects. The authors propose five points for evaluating behavioral genetic studies' conceptualization of environment and use those points to evaluate three exemplary recent studies.

Do the Predictors of Child Conduct Problems Vary by High- and Low-Levels of Socioeconomic and Neighborhood Risk?

This review seeks to examine whether the existing literature on child conduct problems (CP) supports the notion that certain CP risk factors vary in their importance across disadvantaged and better-off environments. Disadvantaged environments are represented by socioeconomic and/or neighborhood risk (SN risk) in this review. Three types of studies were reviewed: behavioral genetic studies that compare the importance of genetic and environmental influences on CP for youth from poor homes and/or disadvantaged communities versus youth from better-off contexts, studies that examine how SN risk and other CP risk factors interact, and studies that compare the antecedents for CP across levels of SN risk. Findings were inconsistent about the manner in which individual child risk factors interact with SN risk. However, familial risk factors were generally found to be of greater importance for youth from poor families and disadvantaged communities, particularly parental supervision. Most of the studies that indicated otherwise focused on physical discipline, or were limited to children from disadvantaged and extremely deprived environments. The findings suggest that in extremely deprived environments, familial influences are overwhelmed by the pervasiveness of other CP risk factors such as deviant peers. Implications for intervention and suggestions for future research are discussed.

Rodent models: Utility for candidate gene studies in human attention-deficit hyperactivity disorder (ADHD)

Attention-deficit hyperactivity disorder (ADHD) is a common neurobehavioral disorder defined by symptoms of developmentally inappropriate inattention, impulsivity and hyperactivity. Behavioral genetic studies provide overwhelming evidence for a significant genetic role in the pathogenesis of the disorder. Rodent models have proven extremely useful in helping understand more about the genetic basis of ADHD in humans. A number of well-characterized rodent models have been proposed, consisting of inbred strains, selected lines, genetic knockouts, and transgenic animals, which have been used to inform candidate gene studies in ADHD. In addition to providing information about the dysregulation of known candidate genes, rodents are excellent tools for the identification of novel ADHD candidate genes. While not yet widely used to identify genes for ADHD-like behaviors in rodents, quantitative trait loci (QTL) mapping approaches using recombinant inbred strains, heterogeneous stock mice, and chemically mutated animals have the potential to revolutionize our understanding of the genetic basis of ADHD.

Childhood antecedents of personality disorder

Given the substantial continuity of personality and axis I psychopathology from childhood to adult life, the present review explores whether and how recent research findings support the notion that personality disorders have their developmental precipitants in childhood. Potential childhood personality disorder antecedents will be reviewed from different research areas to enhance an insight into the genesis of a major set of adult psychiatric disorders with profound impact on the daily life. There exists increasing evidence that personality disorders have their origins in early years of life at the observable symptomatic, biological, and genetic levels. A clear need for prospective (behavior genetic) studies, however, exists that will ultimately verify how and when childhood personality disorder features turn into adult maladaptive trait patterns. It is further suggested that these designs require a comprehensive taxonomy for the description of personality disorder antecedents in a developmentally appropriate way. The call for a developmental perspective on adult personality disorders in recent debates on the construction of Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, has created new avenues for an integrative longitudinal perspective on personality disorders and should stimulate child psychiatrists to consider the significance of emerging personality disorder symptoms at a young age.

Genes and Developmental Stabiltiy of Aggressive Behavior Problems at Home and School in a Community Sample of Twins Aged 7–12

Though behavioral genetic studies of aggression have implicated heritable and environmental factors, there is limited understanding of how these factors influence aggression across different settings and over time. Ratings for 732 twins were collected from parents and teachers during middle childhood and early adolescence. Total aggression scores on the Child Behavioral Checklist (CBCL) and Teacher Report Form (TRF) were examined at each age, across both settings, and developmentally. In this sample, aggressive behavior was moderately to largely heritable at each age within the home (.76-.84) and school (.42-.61). Across each age, ratings by parents and teachers were moderately correlated (.19-.36). Genetic and environmental effects that were limited to a particular setting were important etiological factors for aggressive behavior consistently within each setting, while only genetic factors influenced levels of aggression across both settings. Stability during these ages was due to genetic effects common to each age and the persistence of child-specific environmental experiences within each setting. These results suggest that genetic and environmental influences on children's aggressive behavior are largely setting specific. Levels of aggression seen consistently across both settings are due to genetic influences. Developmentally stable levels of aggressive behavior result from genetic influences common to all ages and individual environmental influences whose effects persist across ages.

One-Trial Associative Odor Learning in Neonatal Mice

Behavior genetics studies in mice demand efficient training protocols for rapid phenotypic screening. However, the capacity of neonatal mice to form and retain associative memories has been difficult to study due to their limited sensorimotor capacities. The present study describes a method for robust, naturalistic associative learning in neonatal mice as young as 3 days old. After removal of the dam from the home cage for 2 h, preweanling CD-1 mice of ages 3, 5, and 10 days postnatal were conditioned to associate an arbitrary odorant with the suckling and milk delivery that ensued upon her return to the home cage. After a second maternal deprivation, neonates were tested on their acquired preference for that odorant. Neonates exhibited a learned preference for the conditioned odorant over a novel control odorant. No learning was observed without deprivation, that is, when the dam was removed only briefly for scenting. One-trial learning sufficed to show clear preferences for the conditioned odorant, although repeated training (three sessions over 8 days) significantly increased the expression of preference. The development of neonatal associative learning protocols requiring minimal human intervention is important for the behavioral phenotyping of mutant and transgenic strains, particularly those modeling developmental disorders.

S.02.03 Genetic vulnerabilities for ADHD

Results of behavioral genetic and molecular genetic studies have converged to suggest that both genetic and nongenetic factors contribute to the development of attention-deficit/hyperactivity disorder (ADHD). We review this literature, with a particular emphasis on molecular genetic studies. Family, twin, and adoption studies provide compelling evidence that genes play a strong role in mediating susceptibility to ADHD. This fact is most clearly seen in the 20 extant twin studies, which estimate the heritability of ADHD to be .76. Molecular genetic studies suggest that the genetic architecture of ADHD is complex. The few genome-wide scans conducted thus far are not conclusive. In contrast, the many candidate gene studies of ADHD have produced substantial evidence implicating several genes in the etiology of the disorder. For the eight genes for which the same variant has been studied in three or more case-control or family-based studies, seven show statistically significant evidence of association with ADHD on the basis of the pooled odds ratio across studies: DRD4, DRD5, DAT, DBH, 5-HTT, HTR1B, and SNAP-25.

In search of shared and nonshared environmental factors in security of attachment: A behavior-genetic study of the association between sensitivity and attachment security.

The current article presents results from a twin study of genetic and environmental components of maternal sensitivity and infant attachment and their association. The sample consisted of 136 twin pairs from 2 sites: Leiden, the Netherlands, and London, UK. Maternal sensitivity was assessed in the home at 9-10 months, and infant attachment security was observed in the laboratory at 12 months. The study yielded little evidence that genetic factors are involved in variations between twins in maternal sensitivity ratings but did find that shared variance in maternal sensitivity was able to account for some of the similarity between twins in attachment security. Weak nonshared associations between sensitivity and attachment appeared to suppress the magnitude of the correlation between attachment and sensitivity in twin children. The results could indicate that the attachment security of one twin may depend on the relationship the parent has with the other twin. The results are brought to bear on the validity of attachment theory as a theory of primarily shared environmental effects in children's development and the continuing challenge posed to attachment theory by within-family differences in socioemotional processes.

Isolation and characterization of seven polymorphic microsatellite loci in the box jellyfish (Chironex fleckeri, Cubozoa, Cnidaria)

AbstractPopulation structure and migration patterns for the highly venomous cubozoan box jellyfish (Chironex fleckeri) are unknown. We describe the development of seven polymorphic microsatellites for this species, the first such loci to be characterized for any cubozoan or indeed cnidarian species other than some corals. These markers will be suitable for use in population and behavioural genetic studies.

Apports de la neurobiologie en psychiatrie de l'enfant et de l'adolescent

Recent findings in neurosciences are reviewed and applied to the domain of child and adolescent psychiatry, especially ADHD and PTSD in childhood. Behavioral genetics studies highlight a bidirectional relationship between genetic and environmental factors which interact at a certain critical period during the child development. fMRI and cognitive studies in turn reveal the brain plasticity which reflects that interplay between genes and environment both at a cellular level and at the level of the neural circuitry. In keeping with those experiments, a new neurocognitive model emerges, the forward model, wherein motor and emotional aspects of an experience are imprinted in our neural networks. This neural template is then automatically and non-consciously activated when the person is interacting with another one. Applied to PTSD and ADHD, this model suggests that the therapeutic challenge which is carried along with such disorders is to prevent the youth from re-activating such a neural template. If our understanding of the child psychopathology is stimulated by neurosciences findings, the therapeutic apparatus is enlarged as well with such new venues as the computerized-assisted cognitive remediation for ADHD. Such computer devices are used to elicit the activation of new neural networks and to help out the youth inhibiting the activation of the non-adaptative previous neural pathways.

Behavior Genetics Principles: Perspectives in Development, Personality, and Psychopathology

Back to table of contents Previous article Next article Book Forum: Behavioral GeneticsFull AccessBehavior Genetics Principles: Perspectives in Development, Personality, and PsychopathologyWILLIAM S. KREMEN, Ph.D., WILLIAM S. KREMENSearch for more papers by this author, Ph.D., La Jolla, Calif.Published Online:1 Oct 2005https://doi.org/10.1176/appi.ajp.162.10.1991AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InEmail This book is a fitting tribute to Irving I. Gottesman by his colleagues and former students. There is a brief overview of behavioral genetic designs that helps to make it accessible for those who are unfamiliar with these methodologies. This overview is followed by chapters on substantive findings regarding genetic and environmental influences on topics as wide-ranging as schizophrenia, substance abuse, social attitudes, the relationship of personality and temperament to psychopathology, and ways in which marital status interacts with genotype to influence behavioral and health outcomes.Several chapters are of interest for how they demonstrate the importance of genetically informative designs for interpreting data as much as for their substantive findings. David DiLalla and Greg Carey, for example, write about personality and psychopathology, but, perhaps more importantly, they illustrate the advantages of a genetically informative design and one way in which examining phenotypic correlations alone can be misleading.In a thought-provoking chapter, Eric Turkheimer discusses the fact that behavioral genetic studies consistently find little effect of shared familial environments. He suggests that other social scientists are still probably correct in asserting that the family in which we are raised does make a difference, but his simulations suggest that the effects of shared environment are obscured in human studies because random genotypes cancel out differential environmental effects. Arguments are put forth from both sides, showing us that the nature-nurture debate is not dead yet. Everyone agrees that both genes and environment are important in development and behavior, but beyond that most general pronouncement the different camps are still competing over which is really most important.The chapter by Daniel Hanson presents a provocative theory of schizophrenia. Thinking outside the box, he suggests that schizophrenia may be analogous to a disease such as polio in which only 1%–2% of those exposed to the virus develop paralysis. Consequently, paralysis may not be the most useful phenotype to study. Moreover, there may not be genes for the illness per se but, rather, genes that confer resistance. This raises another important issue for psychiatric genetic research—the need to consider alternate phenotypes.Although everyone now understands that both genes and environment are important, behavioral genetics is still a long way from being a central part of training in either psychiatry or psychology research. I continue to be struck by the fact that one of the most common questions I am asked about my own twin research is still, “Are they all identical?” To the behavioral genetics researcher, of course, this conveys a lack of basic understanding of the method. Yet with recent advances in molecular genetics and genomics, understanding behavioral genetics and conducting research that is genetically informative will surely become increasingly important. With these concerns in mind, this book serves as an excellent introduction for newcomers to behavioral genetics, while it also addresses sophisticated and provocative issues that will be both interesting and useful to more seasoned researchers.Edited by Lisabeth Fisher DiLalla, Ph.D. Washington, D.C., American Psychological Association, 2004, 239 pp., $59.95. FiguresReferencesCited byDetailsCited ByNone Volume 162Issue 10 October 2005Pages 1991-1991 Metrics PDF download History Published online 1 October 2005 Published in print 1 October 2005

Behaviour genetics ofDrosophila: Non-sexual behaviour

The analysis of genetic behaviour within and between species provides important clues about the forces shaping the evolution of behavioural genes. Genes can affect natural behavioural variation in different ways. Allelic variation causes alternative behavioural phenotypes, whereas changes in gene expression can influence the initiation of behaviour at different ages. Identifying the genes involved in polygenic traits has been difficult. Chromosomal analysis has been widely used as a first step in elucidating the genetic architecture of several behaviours ofDrosophila. Behavioural genetic and molecular studies helped to reveal the genetic basis of circadian time keeping and rhythmic behaviours. InDrosophila, a number of key processes such as emergence from the pupal case, locomotor activity, feeding, olfaction and aspects of mating behaviour are under circadian regulation. Evolutionary biology considers migration behaviour as central in genetic structure of populations and speciation. Genetic loci that influence behaviour are often difficult to identify and localise in part due to the quantitative nature of behavioural phenotypes. Diapause is a hormonally mediated delayed response to future adverse conditions and can occur at any stage of development in an insect. Diapauseassociated gene expression was studied inDrosophila using subtractive hybridisation. Several approaches have been made to unravel the genetic complexity of the behaviour, which have provided information that may be useful in different ways. There is evidence that species do differ in genetic architecture of photoresponse and this may be related to their natural environment. The classical experiments by Jerry Hirsh and Th. Dobzhansky to know the nature of genetic basis for extreme selected geotactic behaviour in fruit flies constituted the first attempt at the genetic dissection of a complex, polygenic behaviour. Understanding the genetic differences between these selected lines would provide an important point of entry into the study of genetic mechanisms of sensing and responding to gravity, as well as clues to the origins of genetic flexibility and plasticity in an organism’s response.

The genetic contribution to canine personality

The domestic dog may be exceptionally well suited for behavioral genetic studies owing to its population history and the striking behavior differences among breeds. To explore to what extent and how behavioral traits are transmitted between generations, heritabilities and genetic correlations for behavioral traits were estimated in a cohort containing over 10,000 behaviorally tested German shepherd and Rottweiler dogs. In both breeds, the pattern of co-inheritance was found to be similar for the 16 examined behavioral traits. Furthermore, over 50% of the additive genetic variation of the behavioral traits could be explained by one underlying principal component, indicating a shared genetic component behind most of the examined behavioral traits. Only aggression appears to be inherited independently of the other traits. The results support a genetic basis for a broad personality trait previously named shyness-boldness dimension, and heritability was estimated to be 0.25 in the two breeds. Therefore, breeds of dogs appear to constitute a valuable resource for behavioral genetic research on the normal behavioral differences in broad personality traits.