Sample Of Twins Research Articles

The chemical evolution of the Milky Way thin disk using solar twins

In this study we address whether the age--metallicity relation (AMR) deviates from the expected trend of metallicity increasing smoothly with age. We also show the presence (or absence) of two populations, as recently claimed using a relatively small dataset. Moreover, we studied the Milky Way thin disk's chemical evolution using solar twins, including the effect of radial migration and accretion events. In particular, we exploited high-resolution spectroscopy of a large sample of solar twins in tandem with an accurate age determination to investigate the Milky Way thin disk age--metallicity relationship. Additionally, we derived the stars' birth radius and studied the chemical evolution of the thin disk. We discovered that statistical and selection biases can lead to a misinterpretation of the observational data. An accurate accounting of all the uncertainties led us to detect no separation in the AMR into different populations for solar twins around the Sun ($-0.3 < Fe/H < 0.3$ dex). This lead us to the conclusion that the thin disk was formed relatively smoothly. For the main scenario of the Milky Way thin disk formation, we suggest that the main mechanism for reaching today's chemical composition around the Sun is radial migration with the possible contribution of well-known accretion events such as Gaia -Enceladus/Sausage (GES) and Sagittarius (Sgr).

Anorexia nervosa polygenic risk, beyond diagnoses: relationship with adolescent disordered eating and behaviors in an Australian female twin population.

It is well established that there is a substantial genetic component to eating disorders (EDs). Polygenic risk scores (PRSs) can be used to quantify cumulative genetic risk for a trait at an individual level. Recent studies suggest PRSs for anorexia nervosa (AN) may also predict risk for other disordered eating behaviors, but no study has examined if PRS for AN can predict disordered eating as a global continuous measure. This study aimed to investigate whether PRS for AN predicted overall levels of disordered eating, or specific lifetime disordered eating behaviors, in an Australian adolescent female population. PRSs were calculated based on summary statistics from the largest Psychiatric Genomics Consortium AN genome-wide association study to date. Analyses were performed using genome-wide complex trait analysis to test the associations between AN PRS and disordered eating global scores, avoidance of eating, objective bulimic episodes, self-induced vomiting, and driven exercise in a sample of Australian adolescent female twins recruited from the Australian Twin Registry (N = 383). After applying the false-discovery rate correction, the AN PRS was significantly associated with all disordered eating outcomes. Findings suggest shared genetic etiology across disordered eating presentations and provide insight into the utility of AN PRS for predicting disordered eating behaviors in the general population. In the future, PRSs for EDs may have clinical utility in early disordered eating risk identification, prevention, and intervention.

The interplay of genetic and environmental factors on the morphology of the limbic cortex and hippocampal subfields: Insights from an MRI twin study

IntroductionThe limbic system and the hippocampus are complex brain structures with key roles in memory, emotions, sexual stimulation and learning, with subregion abnormalities associated with a range of disorders and psychopathologies. Our study aimed to explore the heritability of specific subfield structures within the limbic system and hippocampus first in a Caucasian twin sample with volBrain pipeline. Materials and Methods59 healthy adult Caucasian twin pairs from the Hungarian Twin Registry without any history of previous neurodegenerative or cerebrovascular diseases underwent brain MRI on a 3.0 T scanner (43 monozygotic, MZ and 16 dizygotic, DZ pairs, with a median age of 50±+27 years). The volBrain automated volumetry pipeline was used to calculate the subcortical and general brain volumes from three-dimensional T1-weighted images. Based on age- and sex-adjusted MZ and DZ intra-pair correlations, the univariate ACE model was applied to calculate additive genetic, shared and unshared environmental influences. ResultsAdjusting for age and sex, moderate to strong heritability (A: 59.7 to 73.1 %) was found for most limbic cortex volumes, except for the volumes of entorhinal area and posterior cingulate gyrus where common environmental contribution was detected (C: 56.6 % and 65.0 %, respectively). A substantial heritability (A: 67.0 to 79.4 %) was estimated for the overall hippocampus and most subfield volumes, except for the CA2-CA3 region which was determinated by common environmental factors (C: 45.7 %). Unique environmental variance was a minor to moderate contributor across all variables (E: 20.6 to 54.3 %). ConclusionsAlbeit most limbic cortex, overall hippocampus and most subfield volumes are under substantial genetic influence in healthy adult twins, the volumes of entorhinal area, posterior cingulate gyrus and the CA2-CA3 region of the hippocampus are influenced common environmental factors. The findings underline the importance of unique environmental factors which may play a role in the prevention of disorders related to limbic cortex and hippocampus.

Twin Data Support a Sensitive Period for Singing Ability.

As with many other musical traits, the social environment is a key influence on the development of singing ability. While the familial singing environment is likely to be formative, its role relative to other environmental influences such as training is unclear. We used structural equation modeling to test relationships among demographic characteristics, familial environmental variables (early and current singing with family), vocal training, and singing ability in a large, previously documented sample of Australian twins (N = 1163). Notably, early singing with family, and to a lesser extent vocal training, predicted singing ability, whereas current singing with family did not. Early familial singing also mediated the relationship between sex and singing ability, with men who sang less with family during childhood showing poorer ability. Bivariate twin models between early familial singing and singing ability showed the phenotypic correlation was largely explained by shared environmental influences. This raises the possibility of a sensitive period for singing ability, with sociocultural expectations around singing potentially differentiating the developmental trajectories of this skill for men and women.

Genetic Influence on Social Support: A Twin Study.

Social support is often considered an environmental factor affecting health, especially in aging populations. However, its genetic underpinnings suggest a more complex origin. This study investigates the heritability of social support through applying a threshold model on data of a large adult sample of twins (N = 8019) from the Netherlands Twin Register, collected between 2009 and 2011. The study employed the Duke - UNC Functional Social Support Questionnaire to assess social support quality. Our analysis revealed genetic contributions to social support, with heritability estimated at 37%, without a contribution of shared environment and no differences between men and women in heritability. The study's results underscore the complexity of social support as a trait influenced by genetic and environmental factors, challenging the notion that it is solely an environmental construct.

Dynamics in the heritability of leadership role occupancy: Evidence from a three-wave twin sample

Studies show that genetics matter in who becomes a leader. However, we know little about the dynamic properties of the heritability of leadership emergence or how genetics might interact with environmental conditions to shape leadership emergence. We track leadership role occupancy at three time points among a cohort of 1,079 Danish twin pairs over ten years. Our results suggest that genetics matter less when the cohort is young and increase over time as the cohort grows older. We argue that labor market entry costs coupled with free access to education constrain the effect of genetics in the cohort during early adulthood, suggesting differing effects of the environment on genetic expression as the cohort ages. Sorting based on individual predisposition towards leadership likely strengthens as the cohort grows older and gains labor market experience. This result implies that we should not view the effect of genes on leadership role occupancy as static and that environmental experiences could disproportionately affect critical early leadership advancement. Our study reinforces calls to consider dynamic properties such as gene x environment interactions to advance our broader understanding of leadership’s biology.

Why does perceived parenting in adolescence predict maladaptive personality in adulthood? Evidence for substantial genetic mediation.

Why is parenting in adolescence predictive of maladaptive personality in adulthood? This study sets out to investigate environmental and genetic factors underlying the association between parenting and maladaptive personality longitudinally in a large sample of twins. The present study addressed this question via a longitudinal study focused on two cohorts of twins assessed on aspects of perceived parenting (parent- and adolescent-reported) at age 14 years (n =1,094 pairs). Participants were followed to adulthood, and maladaptive personality traits were self-reported using the Personality Inventory for DSM-5 (PID-5) at age 24 or 34 years. We then modeled these data using a bivariate biometric model, decomposing parenting-maladaptive personality associations into additive genetic, shared environmental, and nonshared environmental factors. Numerous domains of adolescent-reported parenting predicted adult maladaptive personality. Further, we found evidence for substantial additive genetic (r a ranging from 0.22 to 0.55) and (to a lesser extent) nonshared environmental factors (r e ranging from 0.10 to 0.15) that accounted for the association between perceived parenting reported in adolescence and adult personality. Perceived parenting in adolescence and maladaptive personality in adulthood may be related due to some of the same genetic factors contributing to both phenotypes at different developmental periods.

Heritability of movie-evoked brain activity and connectivity.

The neural bases of sensory processing are conserved across people, but no two individuals experience the same stimulus in exactly the same way. Recent work has established that the idiosyncratic nature of subjective experience is underpinned by individual variability in brain responses to sensory information. However, the fundamental origins of this individual variability have yet to be systematically investigated. Here, we establish a genetic basis for individual differences in sensory processing by quantifying (1) the heritability of high-dimensional brain responses to movies and (2) the extent to which this heritability is grounded in lower-level aspects of brain function. Specifically, we leverage 7T fMRI data collected from a twin sample to first show that movie-evoked brain activity and connectivity patterns are heritable across the cortex. Next, we use hyperalignment to decompose this heritability into genetic similarity in where vs. how sensory information is processed. Finally, we show that the heritability of brain activity patterns can be partially explained by the heritability of the neural timescale, a one-dimensional measure of local circuit functioning. These results demonstrate that brain responses to complex stimuli are heritable, and that this heritability is due, in part, to genetic control over stable aspects of brain function.

Methylome-wide association study of multidimensional resilience.

Although resilient youth provide an important model of successful adaptation to adversity, we know relatively little about the origins of their positive outcomes, particularly the role of biological mechanisms. The current study employed a series of methylome-wide association studies to identify methylomic biomarkers of resilience in a unique sample of 276 twins within 141 families residing in disadvantaged neighborhoods. Results revealed methylome-wide significant differentially methylated probes (DMPs) for social and academic resilience and suggestive DMPs for psychological resilience and resilience across domains. Pathway analyses informed our understanding of the biological underpinnings of significant differentially methylated probes. Monozygotic twin difference analyses were then employed to narrow in on DMPs that were specifically environmental in origin. Our findings suggest that alterations in the DNA methylome may be implicated in youth resilience to neighborhood adversity and that some of the suggestive DMPs may be environmentally engendered. Importantly, our ability to replicate our findings in a well-powered sample was hindered by the scarcity of twin samples with youth exposed to moderate to substantial levels of adversity. Thus, although preliminary, the present study is the first to identify DNA methylation biomarkers of academic and social resilience.

Causality of Hashimoto's Thyroiditis to Thyroid Cancer: A 2-S Mendelian Randomization Study

BackgroundObservational studies have indicated an association between Hashimoto's thyroiditis (HT) and the risk of thyroid cancer (TC); however, the causality and direction of these effects in genetics remain unclear. Therefore, our study aims to investigate the relationship between genetic susceptibility to HT and TC through a bidirectional Mendelian randomization (MR) approach using twin samples. MethodsMR analysis was conducted using genetic instruments associated with HT, selected from a comprehensive genome-wide association meta-analysis involving a total of 756 000 individuals of European and East Asian descent. The data set for TC comprised 1.486 million individuals, including both European and East Asian populations. Single nucleotide polymorphisms closely linked to HT were derived from genome-wide association studies. Two-sample bidirectional MR analyses were applied to assess the causal association between HT and TC, using inverse-variance weighted methods, and MR Egger, weighted median, simple mode, and weighted mode. Furthermore, sensitivity analyses were conducted employing the MR-Egger regression model, weighted median method, MR pleiotropy residual sum and outlier, and leave-one-out technique. ResultsMR analyses revealed no evidence of a causal relationship between HT and TC in either European or East Asian populations (all P > .1). However, bidirectional MR analysis demonstrated a causal relationship between TC and HT in the European population (odds ratio = 1.0838, 95% confidence interval: 1.0346, 11 354, P = .000686). ConclusionThis MR analysis indicates a lack of evidence supporting an association between genetically predicted HT and the risk of developing TC. In contrast, there is evidence of a causal relationship between genetically predicted TC and HT.

The world as I see it: genetic and environmental influences on primal world beliefs in a large Swedish twin sample

ABSTRACT Beliefs about the general character of the world – called primals – have received much attention in recent years. Primals (e.g. believing that the world is safe) are associated with psychological and social outcomes, such as personality traits, character strengths and life satisfaction. We performed the first study of genetic and environmental influences on primals, and explored phenotypic associations between primals and the big five personality traits, in a large (~9000) population-wide Swedish twin sample. Correlations between primals and personality traits were low to moderate. Broad-sense heritability estimates of primals ranged between 21% and 49%, suggesting that genetic factors contribute significantly to people’s beliefs about the general character of the world. In contrast, we found little support for shared environmental effects (e.g. rearing environment). Conclusively, we demonstrate that primals and personality are related, yet distinct, constructs and that individual differences in primals depend on both genetic and non-shared environmental factors.

Testing the causal impact of amyloidosis on total Tau using a genetically informative sample of adult male twins.

The amyloid cascade hypothesis predicts that amyloid-beta (Aβ) aggregation drives tau tangle accumulation. We tested competing causal and non-causal hypotheses regarding the direction of causation between Aβ40 and Aβ42 and total Tau (t-Tau) plasma biomarkers. Plasma Aβ40, Aβ42, t-Tau, and neurofilament light chain (NFL) were measured in 1,035 men (mean = 67.0 years) using Simoa immunoassays. Genetically informative twin modeling tested the direction of causation between Aβs and t-Tau. No clear evidence that Aβ40 or Aβ42 directly causes changes in t-Tau was observed; the alternative causal hypotheses also fit the data well. In contrast, exploratory analyses suggested a causal impact of the Aβ biomarkers on NFL. Separately, reciprocal causation was observed between t-Tau and NFL. Plasma Aβ40 or Aβ42 do not appear to have a direct causal impact on t-Tau. In contrast, Aβ aggregation may causally impact NFL in cognitively unimpaired men in their late 60s.

Association between twin status with cognitive, behavioral development and brain structure in early adolescence: a retrospective cohort analysis based on the Adolescent Brain Cognitive Development Study.

Twin births are related with maternal and fetal adverse outcomes. Little was known about the comparability of the cognitive, behavioral development and brain structure between twins and singletons in early adolescence. This retrospective cohort study was based on data from the United States population-based, prospective, longitudinal observational Adolescent Brain Cognitive Development study. Children with complete twin status information were enrolled, and the exposure variable was twin status. Primary outcomes were cognitive, behavioral development and brain structure in early adolescence. Cognitive and behavioral outcomes were assessed by using the NIH Toolbox and Child Behavioral Checklist, respectively. Brain structure was evaluated by the cortical thickness, area, and volume extracted from the magnetic resonance imaging (MRI) data. Subgroup analyses were conducted by prematurity, birth weight, with sibling, genetic profiles, and twin types (zygosity). From 1st September 2016 to 15th November 2018, 11545 children (9477 singletons and 2068 twins) aged 9-10years were enrolled. Twins showed mildly lower cognitive performance (|t|> 5.104, P-values < 0.001, False Discovery Rate [FDR] < 0.001), better behavioral outcome (|t|> 2.441, P-values < 0.015, FDR < 0.042), such as lower scores for multiple psychiatric disorders and behavioral issues, and smaller cortical volume (t = - 3.854, P-values < 0.001, FDR < 0.001) and cortical area (t = - 3.872, P-values < 0.001, FDR < 0.001). The observed differences still held when stratified for prematurity, birth weight, presence of siblings, genetic profiles, and twin types (zygosity). Furthermore, analyses on the two-year follow-up data showed consistent results with baseline data. Twin status is associated with lower cognitive and better behavioral development in early adolescence accompanied by altered brain structure. Clinicians should be aware of the possible difference when generalizing results from adolescent twin samples to singletons.

The Influence of Maternal and Paternal Parenting on Adolescent Brain Structure

BackgroundAdolescents raised in families with different maternal and paternal parenting combinations exhibit variations in neurocognition and psychopathology; however, whether neural differences exist remains unexplored. This study used a longitudinal twin sample to delineate how different parenting combinations influence adolescent brain structure and to elucidate the genetic contribution. MethodsA cohort of 216 twins participated in parenting assessments during early adolescence and underwent magnetic resonance imaging scanning during middle adolescence. We utilized latent profile analysis to distinguish between various maternal and paternal parenting profiles and subsequently investigated their influences on brain anatomy. Biometric analysis was applied to assess genetic influences on brain structure, and associations with internalizing symptoms were explored. ResultsIn early adolescence, 4 parenting profiles emerged, which were characterized by levels of harshness and hostility in one or both parents. Compared with adolescents in “catparent” families (low harshness/hostility in both parents), those raised in “tigermom” families (harsh/hostile mother only) exhibited a smaller nucleus accumbens volume and larger temporal cortex surface area; those in “tigerdad” families demonstrated larger thalamus volumes; and those in “tigerparent” families displayed smaller volumes in the midanterior corpus callosum. Genetic risk factors contributed significantly to the observed brain structural heterogeneity and internalizing symptoms. However, the influences of parenting profiles and brain structure on internalizing symptoms were not significant. ConclusionsThe findings underscore distinct brain structural features linked to maternal and paternal parenting combinations, particularly in terms of subcortical volume and cortical surface area. This study suggests an interdependent role of maternal and paternal parenting in shaping adolescent neurodevelopment.

Prospective Effects of Self-Rated Health on Dementia Risk in Two Twin Studies of Aging

Subjective health ratings are associated with dementia risk such that those who rate their health more poorly have increased risk for dementia. The genetic and environmental mechanisms underlying this association are unclear, as prior research cannot rule out whether the association is due to genetic confounds. The current study addresses this gap in two samples of twins, one from Sweden (N = 548) and one from Denmark (N = 4,373). Using genetically-informed, bivariate regression models, we assessed whether additive genetic effects explained the association between subjective health and dementia risk as indexed by a latent variable proxy measure. Age at intake, sex, education, depressive symptomatology, and follow-up time between subjective health and dementia risk assessments were included as covariates. Results indicate that genetic variance and other sources of confounding accounted for the majority of the effect of subjective health ratings on dementia risk. After adjusting for genetic confounding and other covariates, a small correlation was observed between subjective health and latent dementia risk in the Danish sample (rE = − .09, p < .05). The results provide further support for the genetic association between subjective health and dementia risk, and also suggest that subjective ratings of health measures may be useful for predicting dementia risk.

Effect of identical twins on deep speaker embeddings based forensic voice comparison

Deep learning has gained widespread adoption in forensic voice comparison in recent years. It is mainly used to learn speaker representations, known as embedding features or vectors. In this work, the effect of identical twins on two state-of-the-art deep speaker embedding methods was investigated with special focus on metrics of forensic voice comparison. The speaker verification performance has been assessed using the likelihood-ratio framework by likelihood ratio cost and equal error rate. The AVTD twin speech dataset was applied. The results show a significant reduction in speaker verification performance when twin samples are present. Neither the adaptation of LR score calculation to twin samples, nor fine-tuning the pre-trained speaker embedding models seemed to be able to leverage this limitation. It was found that the recognition of same or different speakers was possible even in the case of identical twins but the performance dropped greatly. The lowest EER of the best performing model was 3.4% in the case of non-twin; at the same time, EER was 25.3% when twins were present. This doesn’t mean that the presented methods are useless in case of identical twins, but it must be taken into consideration that in case of a higher likelihood-ratio score (which indicates same speakers on the tested samples), the possibility of twins must also be considered in a real casework.

Attachment and Political Personality are Heritable and Distinct Systems, and Both Share Genetics with Interpersonal Trust and Altruism

The attachment and caregiving domains maintain proximity and care-giving behavior between parents and offspring, in a way that has been argued to shape people’s mental models of how relationships work, resulting in secure, anxious or avoidant interpersonal styles in adulthood. Several theorists have suggested that the attachment system is closely connected to orientations and behaviors in social and political domains, which should be grounded in the same set of familial experiences as are the different attachment styles. We use a sample of Norwegian twins (N = 1987) to assess the genetic and environmental relationship between attachment, trust, altruism, right-wing authoritarianism (RWA), and social dominance orientation (SDO). Results indicate no shared environmental overlap between attachment and ideology, nor even between the attachment styles or between the ideological traits, challenging conventional wisdom in developmental, social, and political psychology. Rather, evidence supports two functionally distinct systems, one for navigating intimate relationships (attachment) and one for navigating social hierarchies (RWA/SDO), with genetic overlap between traits within each system, and two distinct genetic linkages to trust and altruism. This is counter-posed to theoretical perspectives that link attachment, ideology, and interpersonal orientations through early relational experiences.

The longitudinal relationship between life events and loneliness in adolescence: A twin study.

The aim of the study was to examine associations between life events and self-assessed loneliness in adolescence. We used data from a Norwegian population-based twin sample including seven birth cohorts (N = 2,879, 56% females). The participants completed self-report questionnaires three times throughout adolescence, with 2 years in between (i.e., 12-18 years old at Wave 1). By using a random intercept cross-lagged panel model (RI-CLPM), we were able to separate stable influences in the measured constructs from the within-person changes at each measurement occasion. In addition, using data from twins allowed us to examine to what degree the associations between life events and loneliness were genetic and/or environmental in nature. The results showed moderate stability of both loneliness and aggregation scores of life events throughout adolescence. The life events were assigned to clusters based on their independence (i.e., events considered dependent or independent on a person's behavior) and desirability (i.e., positive or negative). The time-stable between-person variance in all three measures, loneliness and person-dependent positive and negative life events, could almost exclusively be accounted for by genetic factors. However, as expected, also shared environmental factors influenced person-independent life events. The associations between time-stable between-person variance in loneliness and life events were small, and nearly exclusively due to shared genetic influences. Furthermore, life events do not seem to predict changes in loneliness or vice versa. In conclusion, the self-reported levels of loneliness throughout adolescence seems to be independent of life events. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

The genetics of intelligence and social outcomes in a Hungarian twin sample

Most previous research found that within-family resemblance on social outcomes and intelligence is mostly due to genetic factors with a limited role of the shared environment, with the exception of educational attainment. Hypotheses about a gene-environment interaction with SES, with a presumably smaller role of genetic factors in families with low social status, have been only partially confirmed. However, these results do not necessarily generalize to all societies, and data from Central or Eastern European countries is currently deficient. In the current work we replicate using data from the Hungarian Twin Registry that intelligence, income, and educational attainment are substantially heritable, with limited role of the shared environment. In contrast to studies in Anglo-Saxon or Western European countries, we found an influence of the shared environment on standardized high school test scores, especially history. Both genetic and shared environmental (but not nonshared environmental) correlations were substantial, in line with generalist genes and shared environments but specific nonshared environmental effects. The results show that the heritability of social traits is observable in Central/Eastern Europe, but they highlight a potentially problematic aspect of Hungarian high school final tests, as students' family of origin appears to be a potent determinant of grades.

Cohort Effects on Tobacco Consumption and Its Genetic and Environmental Variance Among Finnish Adults Born Between 1880 and 1957

Abstract Introduction Population research indicates that smoking behaviors in Finland have varied over time by sex and birth cohort. Smoking behaviors are influenced by genes and the environment; like the behaviors themselves, these underlying influences are not necessarily stable over time and may be modifiable by national drug policy. Aims and Methods We utilized longitudinal mixed-effects models and causal–common–contingent twin models to evaluate sex and cohort effects on tobacco consumption and the underlying genetic and environmental variance components in a birth cohort sample of same-sex twins born in Finland between 1880 and 1957, assessed in 1975, 1981, 1990, and 2011. Results We identified significant main effects of age, sex, and cohort on quantity of cigarette consumption, as well as significant age × cohort and sex × cohort interactions. We also identified sex and cohort effects on the liability to initiate regular smoking and the magnitude of variation underlying quantity of cigarette consumption. That said, heritability and environmental contributions to both traits were not different between the four sex × cohort groups. Conclusions Our results indicate sex and cohort effects on the prevalence of smoking and its underlying variation. Our results on changing prevalence mirror existing population-level research in Finnish samples, but we did not identify differences in heritability found in other studies of cohort effects in tobacco use, potentially due to power issues. These results highlight the importance of considering age, cohort, and timing of policy changes when evaluating changes in substance consumption across time. Implications This study identifies sex and cohort effects influencing tobacco consumption in a sample of Finnish adult twins born between 1880 and 1957. Our results are in line with other population-level research in Finland and research on cohort effects influencing alcohol use in the same sample. Our results highlight the intertwining effects of age, cohort, sex, and substance policies on substance use.