Genetic and Environmental Influences on Biological Essentialism, Heuristic Thinking, Need for Closure, and Conservative Values: Insights From a Survey and Twin Study.

Biological essentialism, the belief that human attributes are determined by biology, is a core component of essentialist thinking. Previous studies have shown that individual differences in essentialist thinking are associated with heuristic thinking, cognitive ability and style, conservative values, and prejudice. None, however, have examined whether biological essentialism is itself heritable, or the extent to which familial aggregation explains associations with core correlates. In order to do this, we analyzed data from a genetically informative sample of families with twins in Australia (N = 2,103), as well as general population samples from the UK (N = 501) and the US (N = 500). Genetic factors had little influence in individual differences in biological essentialism or in its relationship with heuristic thinking. Conservative values were genetically correlated with cognitive styles (i.e., need for closure and heuristic thinking). These findings support a bigger role of genes in explaining the relationship between cognitive processes and moral reasoning and ideology than they do the association between cognitive processes and essentialist thinking.

Public Understanding of Behavioral Genetics: Integrating Heuristic Thinking, Motivated Reasoning and Planned Social Change Theories for Better Communication Strategies.

The field of behavioral genetics is experiencing a revolution following the development of genome-wide association studies and the availability of large datasets from international consortia. This rapid change could increase the existing gaps between basic research, translation, and public understanding of science. In the present work, we aim to synthesize key explanations of how public understanding of socio-scientific issues develop. We propose that integrating dual-process, motivated reasoning, and change management theories will increase the extent to which we understand, and can change, how people respond to findings from behavior genetics.

A direct test of the diathesis-stress model for depression.

The diathesis-stress theory for depression states that the effects of stress on the depression risk are dependent on the diathesis or vulnerability, implying multiplicative interactive effects on the liability scale. We used polygenic risk scores for major depressive disorder (MDD) calculated from the results of the most recent analysis from the Psychiatric Genomics Consortium as a direct measure of the vulnerability for depression in a sample of 5221 individuals from 3083 families. In the same we also had measures of stressful life events and social support and a depression symptom score, as well as DSM-IV MDD diagnoses for most individuals. In order to estimate the variance in depression explained by the genetic vulnerability, the stressors and their interactions, we fitted linear mixed models controlling for relatedness for the whole sample as well as stratified by sex. We show a significant interaction of the polygenic risk scores with personal life events (0.12% of variance explained, P-value=0.0076) contributing positively to the risk of depression. Additionally, our results suggest possible differences in the aetiology of depression between women and men. In conclusion, our findings point to an extra risk for individuals with combined vulnerability and high number of reported personal life events beyond what would be expected from the additive contributions of these factors to the liability for depression, supporting the multiplicative diathesis-stress model for this disease.

The CODATwins Project: The Current Status and Recent Findings of COllaborative Project of Development of Anthropometrical Measures in Twins.

The COllaborative project of Development of Anthropometrical measures in Twins (CODATwins) project is a large international collaborative effort to analyze individual-level phenotype data from twins in multiple cohorts from different environments. The main objective is to study factors that modify genetic and environmental variation of height, body mass index (BMI, kg/m2) and size at birth, and additionally to address other research questions such as long-term consequences of birth size. The project started in 2013 and is open to all twin projects in the world having height and weight measures on twins with information on zygosity. Thus far, 54 twin projects from 24 countries have provided individual-level data. The CODATwins database includes 489,981 twin individuals (228,635 complete twin pairs). Since many twin cohorts have collected longitudinal data, there is a total of 1,049,785 height and weight observations. For many cohorts, we also have information on birth weight and length, own smoking behavior and own or parental education. We found that the heritability estimates of height and BMI systematically changed from infancy to old age. Remarkably, only minor differences in the heritability estimates were found across cultural-geographic regions, measurement time and birth cohort for height and BMI. In addition to genetic epidemiological studies, we looked at associations of height and BMI with education, birth weight and smoking status. Within-family analyses examined differences within same-sex and opposite-sex dizygotic twins in birth size and later development. The CODATwins project demonstrates the feasibility and value of international collaboration to address gene-by-exposure interactions that require large sample sizes and address the effects of different exposures across time, geographical regions and socioeconomic status.

Genome-wide analysis of over 106 000 individuals identifies 9 neuroticism-associated loci.

Neuroticism is a personality trait of fundamental importance for psychological well-being and public health. It is strongly associated with major depressive disorder (MDD) and several other psychiatric conditions. Although neuroticism is heritable, attempts to identify the alleles involved in previous studies have been limited by relatively small sample sizes. Here we report a combined meta-analysis of genome-wide association study (GWAS) of neuroticism that includes 91 370 participants from the UK Biobank cohort, 6659 participants from the Generation Scotland: Scottish Family Health Study (GS:SFHS) and 8687 participants from a QIMR (Queensland Institute of Medical Research) Berghofer Medical Research Institute (QIMR) cohort. All participants were assessed using the same neuroticism instrument, the Eysenck Personality Questionnaire-Revised (EPQ-R-S) Short Form's Neuroticism scale. We found a single-nucleotide polymorphism-based heritability estimate for neuroticism of ∼15% (s.e.=0.7%). Meta-analysis identified nine novel loci associated with neuroticism. The strongest evidence for association was at a locus on chromosome 8 (P=1.5 × 10(-15)) spanning 4 Mb and containing at least 36 genes. Other associated loci included interesting candidate genes on chromosome 1 (GRIK3 (glutamate receptor ionotropic kainate 3)), chromosome 4 (KLHL2 (Kelch-like protein 2)), chromosome 17 (CRHR1 (corticotropin-releasing hormone receptor 1) and MAPT (microtubule-associated protein Tau)) and on chromosome 18 (CELF4 (CUGBP elav-like family member 4)). We found no evidence for genetic differences in the common allelic architecture of neuroticism by sex. By comparing our findings with those of the Psychiatric Genetics Consortia, we identified a strong genetic correlation between neuroticism and MDD and a less strong but significant genetic correlation with schizophrenia, although not with bipolar disorder. Polygenic risk scores derived from the primary UK Biobank sample captured ∼1% of the variance in neuroticism in the GS:SFHS and QIMR samples, although most of the genome-wide significant alleles identified within a UK Biobank-only GWAS of neuroticism were not independently replicated within these cohorts. The identification of nine novel neuroticism-associated loci will drive forward future work on the neurobiology of neuroticism and related phenotypes.

No evidence of association of oxytocin polymorphisms with breastfeeding in 2 independent samples.

Oxytocin has an important function in breastfeeding via its role in the milk ejection reflex and in attachment and bonding processes. Genetic factors account for a significant part of the individual differences in breastfeeding behavior. OXT and OXTR have been proposed as gene candidates for breastfeeding. Previous studies have focused on certain single-nucleotide polymorphisms (SNPs) within these genes, finding null or inconsistent results. The present study analyses the associations between a wide coverage of polymorphisms in OXT and OXTR and breastfeeding duration from 2 large and independent unselected samples comprising a total of 580 and 2112 female twin mothers from the Murcia Twin Registry (Spain) and QIMR Berghofer Medical Research Institute (Australia), respectively. A total of 19 SNPs in OXT and 137 in OXTR SNPs were covered in both samples. Effects of the OXT and OXTR polymorphisms on breastfeeding duration were calculated by means of linear regression controlling for age at survey time, educational level, interaction between age and educational level and principal components of genetic ancestry. The analyses were conducted independently in the 2 samples and also meta-analyzed. Although some SNPs were associated at an alpha level of .05 with breastfeeding, they did not survive multiple testing correction. We conclude that SNPs within or nearby OXT and OXTR are unlikely to have large effects on breastfeeding behavior.

Application of multiparametric procedures for assessing the heritability of circadian health.

At present, the measurement of circadian system status under free-living conditions by the use of sensors is a relatively new technique. The data obtained using these methods are influenced by strong environmental masking factors and artifacts that can affect its recording. Therefore, the use of integrative variables such as TAP, a measure that includes temperature, activity and position that reduces these drawbacks and the number of parameters obtained is necessary. However, the relative genetic contribution to this circadian marker is unknown. The aim of our study was to ascertain the relative importance of genetic influences in TAP, and for each of its components using classical twin models. The study was performed in 53 pairs of female twins [28 monozygotic (MZ) and 25 dizygotic (DZ)] with mean age 52 ± 6 years. Circadian patterns were studied by analyzing temperature, body position and activity for 1 week every 1 min with "Circadianware®.". Genetic influences affecting the variability of each of the measurements were estimated by comparing the observed data in twin pairs. MZ twins showed higher intrapair correlations than DZ twins for most of the parameters. Genetic factors (broad sense heritability) were responsible for about 40-72% of TAP variance in parameters such as mesor, acrophase, amplitude, Rayleigh test, percentage of rhythmicity and circadian function index. We found more homogeneous heritability estimates of the circadian system when using an integrative technique such as TAP than with individual variables alone, suggesting that this measurement can be more reliable and less subject to environmental artifacts.

Obesidad, actividad física y dolor lumbar: un análisis genéticamente informativo / Obesity, physical activity and low back pain: a genetically informative analysis

Objetivo: Analizar la relación entre obesidad, actividad física y dolor lumbar a través de un estudio transversal de gemelos caso-control. Material y método: La muestra general la componen 1.613 individuos gemelos, de entre 47 y 73 años, y participantes en el Registro de Gemelos de Murcia. Los datos fueron obtenidos mediante entrevista telefónica y se recogió información sobre dolor de espalda, datos antropométricos y actividad física. La cigosidad fue evaluada mediante cuestionario. El análisis caso-control se realizó sobre 199 parejas completas y discordantes para dolor lumbar. Resultados: La prevalencia del dolor lumbar en la muestra total fue del 33,1% (mujeres: 36,4%; varones: 29,1%). El Índice de Masa Corporal (IMC) fue de 27.2 (DE: 4,3). En la muestra general, ser mujer, IMC elevado, frecuencia baja de actividad física moderada e intensa y sedentarismo se asociaron con mayor riesgo de padecer dolor lumbar. Sin embargo, todas las asociaciones perdieron significación estadística en el análisis caso-control. Conclusión: Es necesario considerar las características individuales o grupales al valorar el papel del IMC o la actividad física en la prevención del dolor lumbar. Esto incluye la necesidad de tener en cuenta el papel de los factores genéticos en futuras investigaciones sobre esta relación (AU)

Objective: Our main objective was to analyse the relationship between obesity, physical activity and low back pain using a cross-sectional co-twin design. Material and method: The total sample comprised 1,613 subjects, aged 47 to 73, from the Murcia Twin Registry. Data were obtained through telephone interview, and information about back pain, anthropometric data and physical activity was collected. One-hundred and ninety-nine pairs complete and discordant for low back pain were available for the case-control analysis. Results: Prevalence of low back pain was 33.1% (females: 36.4%; males: 29.1%). Mean Body Mass Index (BMI) was 27.2 (SD: 4.3). For the general sample, being female, a high BMI, low frequency of moderate or intense physical activity and sedentarism were associated to a higher risk of low back pain. However, all associations lost statistical significance in the case-control analyses. Conclusion: Individual and group characteristics must be considered when evaluating the role of BMI or physical activity on prevention of low back pain. This includes the need to take into account the role of genetic factors in future research about this relationship (AU)