Genetics of adult attachment: An updated review of the literature

Genetic and environmental contributions to adult attachment styles: Evidence from the Minnesota Twin Registry

Attachment theory, as originally outlined by Bowlby (1973, 1980, 1969/1982), suggests that the ways people think, feel, and behave in close relationships are shaped by the dynamic interplay between their genes and their social environment. Research on adult attachment, however, has largely focused on the latter, providing only a partial picture of how attachment styles emerge and develop throughout life. The present research leveraged data from the Minnesota Twin Registry, a large sample of older adult twins (N = 1,377 twins; 678 pairs; Mage = 70.40 years, SD = 5.42), to examine the relative contributions of genetic and environmental factors to adult attachment styles. Participants reported on both their general attachment styles and relationship-specific attachments to their mothers, fathers, partners, and best friends. The results suggest that attachment styles are partly heritable (∼36%) and partly attributable to environmental factors that are not shared between twins (∼64%). Heritability estimates were somewhat higher for parent-specific attachment styles (∼51%), whereas nonshared environmental factors accounted for larger proportions of the variance in partner- and best friend-specific attachment styles. Using multivariate biometric models, we also examined the genetic and environmental factors underlying the covariation among people's relationship-specific attachment styles. The findings indicate that the similarities among people's avoidant tendencies in different relationships can be explained by a single, higher order latent factor (e.g., global avoidance). In contrast, the genetic and environmental factors underlying attachment anxiety appear to be more differentiated across specific close relationships. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

How does neurochemistry affect attachment styles in humans? The role of oxytocin and the endogenous opioid system in sociotropy and autonomy - A systematic review

Oxytocin was hypothesised to play a critical role in forming and maintaining secure attachments, shown to confer resilience against affective disorders. The endogenous opioid system has also emerged as a key player in attachment dynamics. In this pre-registered systematic review, we investigated whether individual differences in the functioning of these neurochemical systems are related to attachment styles, following PRISMA guidelines. As predicted, individuals with higher oxytocin function exhibited more secure attachment styles (p = .006, n = 12 studies) and less insecure attachment styles (p = .021, n = 16 studies). Contrary to our hypothesis, we found no association of endogenous opioid function with insecure (p = 0.549, n = 11 studies) or secure attachment styles (p = .065, n = 11 studies). The lack of association between endogenous mu-opioid function and attachment styles remains inconclusive due to inconsistencies in the neurochemical measurements and lack of eligible studies. Therefore, further investigations into the role of the endogenous opioid system in attachment styles are needed. Our findings corroborate the hypothesis that individual differences in oxytocin function relate to differences in attachment styles.

Genetic Contributions on Attachment in Emerging Adults: Cumulative Effects of Serotonergic Polymorphisms

Attachment in emerging adults is closely intertwined with emotion regulation, stress coping, and social bonding during the transition from childhood to early adulthood. Due to the critical roles of serotonin in these mental functions, this research explored whether the cumulative genetic effects of serotonergic polymorphisms are associated with individual differences and contextual variations in attachment dimensions over time in emerging adults. Study 1 utilized a cross-sectional design in college students (N = 1088, mean age = 22.71 ± 2.86 years). The results showed significant correlations between a higher cumulative genetic score and elevated levels of attachment anxiety and avoidance. Study 2 employed a three-wave longitudinal design in a cohort of freshmen (N = 523, mean age = 19.54 ± 1.86 years at wave 1). The results demonstrated that a higher genetic score was associated with both higher levels and greater variability in attachment dimensions compared to a lower genetic score. These findings suggest that the cumulative genetic effects of serotonergic polymorphisms contribute to individual differences and dynamic processes in attachment dimensions in emerging adults.

A narrative on the neurobiological roots of attachment-system functioning

Attachment theory is one of the most comprehensive frameworks in social and developmental psychology. It describes how selective, enduring emotional bonds between infants and their caregivers are formed and maintained throughout life. These attachment bonds exhibit distinct characteristics that are intimately tied to fundamental aspects of mammalian life, including pregnancy, birth, lactation, and infant brain development. However, there is a lack of a cohesive biological narrative that explains the psychological forces shaping attachment behavior and the emergence and consolidation of attachment patterns at a neurobiological level. Here, we propose a theoretical narrative focusing on organized attachment patterns that systematically link the two primary purposes of the attachment behavioral system: the provision of tangible protection or support and the corresponding subjective feeling of safety or security. We aim for this detailed delineation of neurobiological circuits to foster more comprehensive and interdisciplinary future research.

Attachment Problems and Mentalizing Capacity Relate to Parent-Child Informant Discrepancies in Female Adolescents with Borderline Personality Disorder

Parent-child informant discrepancies on psychopathology provide important knowledge on the parent-child relationship and the child's mental health, but mechanisms underlying parent-child informant discrepancies are largely unknown. Therefore, we investigated the relationship between attachment problems and mentalizing capacity and parent-child informant discrepancies on borderline personality disorder (BPD) severity, internalizing, and externalizing pathology in a clinical sample of 91 adolescent girls with BPD and their parents. Results showed that more attachment problems to parents and peers were related to adolescents reporting more severe BPD than parents. Adolescents who described more internalizing symptoms relative to parents, reported more parental attachment problems, but enhanced peer attachment, suggesting those adolescents who do not feel recognized by their parents might turn to their friends. When parents rated adolescents higher on externalizing behaviors, the adolescent reported more attachment problems to parents and lower mentalizing capacity, indicating that this sub-group of adolescents may reflect less about how their behavior affects others.

Influence of anxious attachment on the relationship between primary emotions and substance-related addictive behaviors

Objectives

To date there is no universally accepted model that describes the development of substance related addictive behavior. In order to address this gap, the study sought to examine whether the association between primary emotions and the inclination toward addictive behavior is mediated by an anxious attachment style.

Methods

The total sample consisted of 900 German speaking non-clinical adults (age: M = 27; SD = 9.60; 71.6% female). Structural Equation Modeling (SEM) was applied to examine the connection between the primary emotions (SADNESS and ANGER), and the latent variables attachment anxiety and symptoms of addictive behavior.

Results

Substance use symptomatology was correlated with higher attachment anxiety (r = 0.15), SADNESS (r = 0.15), and ANGER (r = 0.11). The effect of SADNESS on addictive behavior is mediated by attachment anxiety (p < 0.01) whereas ANGER had a direct effect on addictive behavior (p < 0.01). The final SEM explains 4% of the variance of addictive behaviors and 22% of attachment anxiety.

Conclusion

Our findings suggest that both SADNESS and ANGER, along with attachment anxiety, are dispositions that contribute to the risk of engaging in addictive behavior. However, while ANGER directly influences addictive behavior, SADNESS acts through its impact on attachment anxiety.

A perspective-based analysis of attachment from prenatal period to second year postnatal life

Attachment is one of the foundational themes in the history of the psychological development of human beings. For this reason, we assume that it must be approached by taking into account multiple scientific perspectives. The present review aims at analyzing the state of the art regarding the genetic, neurobiological and cognitive mechanisms underlying the development of attachment bonding, considering the child as the frame of reference. We hypothesize that attachment may be present in prototypical forms even in the prenatal period, thus our analysis has a temporal origin in the intrauterine period preceding birth. The intrauterine period is assumed to be a period of maximum sensitivity to stimuli and in particular to those coming from a potential primary caregiver: the biological mother. We conclude with a reframing of the state of the art and propose that future research work would benefit from a superordinate model of attachment, capable of containing and regulating all its components and variables.

Genetic Contributions to Attachment Stability Over Time: the Roles of CRHR1 Polymorphisms

Corticotropin-releasing hormone receptor 1 (CRHR1), a hormone receptor essential to the activation of HPA axis and the subsequent release of cortisol, plays critical roles in emotional and behavioral responses relevant to attachment. However, the specific roles of CRHR1 polymorphisms in attachment remain unclear. To further clarify these genetic effects, this research conducted a three-wave study to investigate whether the CRHR1 polymorphisms (i.e., rs110402 and rs242924) are associated with the stability and variability of attachment by using a sample of freshmen (N = 604; Mage = 18.57 years, SD = 1.90; 68.8% girls). The results showed that rs110402 and rs242924 were associated with the stability of closeness-dependence. The G alleles of the both polymorphisms were found not to be related to lower attachment stability. However, these polymorphisms were not associated with the variability of attachment. Overall, these findings provide evidence for the contribution of CRHR1 to attachment stability.

Exploring the role of adult attachment, major depression and childhood trauma in arterial stiffness: A preliminary study

OBJECTIVE

Prior research indicates a noteworthy and intricate connection between depression and subclinical atherosclerosis. Nevertheless, the biological and psychological mechanisms that underlie this association are not yet fully understood. To address this gap, this exploratory study aimed to examine the relationship between active clinical depression and arterial stiffness (AS), with a particular focus on the potential mediating roles of attachment security and childhood trauma.

METHODS

In this cross-sectional study, we examined 38 patients with active major depression free of dyslipidemia, diabetes mellitus, hypertension, and obesity and 32 healthy controls. All participants underwent blood tests, psychometric assessments, and AS measurements using the Mobil-O-Graph arteriograph system. AS severity was evaluated using an augmentation index (AIx) normalized to 75 beats/min.

RESULTS

In the absence of defined clinical cardiovascular risk factors, there was no significant difference in AIx between individuals with depression and healthy controls (p = .75). Patients with longer intervals between depressive episodes had lower AIx (r = -0.44, p < .01). Insecure attachment and childhood trauma did not significantly associate with AIx in patients. Whereas insecure attachment was positively correlated with AIx only in healthy controls (r = 0.50, p = 01).

CONCLUSIONS

Our analysis of established risk factors for atherosclerosis revealed that depression and childhood trauma had no significant relationship with AS. However, we did identify a novel finding: insecure attachment was significantly associated with AS severity in healthy adults without defined cardiovascular risk factors for the first time. To our knowledge, this is the first study to demonstrate this relationship.

Neurobiology of Disorganized Attachment: A Review of Primary Studies on Human Beings

This article describes and analyzes various aspects related to the neurobiology of disorganized attachment (DA), which is associated with personality, eating, affective, dissociative, and addictive disorders. We included primary studies in humans, published in PubMed from 2000 to 2022. Eight genetic and one epigenetic study were considered. Three molecular studies describe possible roles of oxytocin and cortisol, seven neurophysiological studies investigated functional correlates, and five morphological studies describe anatomical changes. Findings in candidate genes involved in dopaminergic, serotonergic, and oxytonergic systems have not been able to be replicated in large-scale human studies. Alterations in the functioning of cortisol and oxytocin are preliminary. Neurophysiological studies show changes in subcortical structures (mainly in the hippocampus) and occipital, temporal, parietal, and insular cortices. Since there is a lack of robust evidence on the neurobiology of DA in humans, the possible inferences of these studies are preliminary, which restricts their translation to clinical parameters.

Genetics of adult attachment and the endogenous opioid system

Since the pioneering work by Panksepp et al, the neurobiological bases of attachment behavior have been closely linked with opioid neurotransmission. Candidate gene studies of adult individuals have shown that variation in the mu-opioid receptor gene (OPRM1) influences attachment behavior. Early maternal care and the A/A genotype of the A118G polymorphism interact in modulating levels of fearful attachment. Compared to their counterparts carrying the A/A genotype, individuals expressing the minor 118G allele show lower levels of avoidant attachment and experience more pleasure in social situations. Brain imaging research has strengthened the biological plausibility of candidate gene studies. The avoidance dimension of attachment correlates negatively with mu-opioid receptor availability in the thalamus and anterior cingulate cortex, as well as the frontal cortex, amygdala, and insula. Overall, findings from human studies combined with those from animal models suggest that research on the genetic bases of attachment should include the endogenous opioid system among the investigated variables.

Genetic Variants Associated With Resilience in Human and Animal Studies

Resilience is broadly defined as the ability to maintain or regain functioning in the face of adversity and is influenced by both environmental and genetic factors. The identification of specific genetic factors and their biological pathways underpinning resilient functioning can help in the identification of common key factors, but heterogeneities in the operationalisation of resilience have hampered advances. We conducted a systematic review of genetic variants associated with resilience to enable the identification of general resilience mechanisms. We adopted broad inclusion criteria for the definition of resilience to capture both human and animal model studies, which use a wide range of resilience definitions and measure very different outcomes. Analyzing 158 studies, we found 71 candidate genes associated with resilience. OPRM1 (Opioid receptor mu 1), NPY (neuropeptide Y), CACNA1C (calcium voltage-gated channel subunit alpha1 C), DCC (deleted in colorectal carcinoma), and FKBP5 (FKBP prolyl isomerase 5) had both animal and human variants associated with resilience, supporting the idea of shared biological pathways. Further, for OPRM1, OXTR (oxytocin receptor), CRHR1 (corticotropin-releasing hormone receptor 1), COMT (catechol-O-methyltransferase), BDNF (brain-derived neurotrophic factor), APOE (apolipoprotein E), and SLC6A4 (solute carrier family 6 member 4), the same allele was associated with resilience across divergent resilience definitions, which suggests these genes may therefore provide a starting point for further research examining commonality in resilience pathways.