Genetic and environmental contributions to the subjective burden of social isolation during the COVID-19 pandemic.

BACKGROUND: Feelings of loneliness and the burden of social isolation were among the most striking consequences of widespread containment measures, such as "social distancing", during the COVID-19 pandemic. Because of the potential impact on people's health, there has been increased interest in understanding the mechanisms and factors that contributed to feelings of loneliness and the burdens of social isolation. However, in this context, genetic predisposition has been largely ignored as an important factor. This is problematic because some of the phenotypic associations observed to date may in fact be genetic. The aim of this study is, therefore, to examine the genetic and environmental contributions to the burden of social isolation at two time points during the pandemic. In addition, we examine whether risk factors identified in previous studies explain genetic or environmental contributions to the burden of social isolation. METHODS: The present study is based on a genetically sensitive design using data from the TwinLife panel study, which surveyed a large sample of adolescent and young adult twins during the first (N = 798) and the second (N = 2520) lockdown in Germany. RESULTS: We find no substantive differences in genetic and environmental contributions to social isolation burden over the course of the pandemic. However, we find the determinants highlighted as important in previous studies can explain only a small proportion of the observed variance in the burden of social isolation and mainly explained genetic contributions. CONCLUSIONS: While some of the observed associations appear to be genetic, our findings underscore the need for further research, as the causes of individual differences in burden of social isolation remain unclear.

Is There Evidence for Intelligence-by-Conscientiousness Interaction in the Prediction of Change in School Grades from Age 11 to 15 Years?

Fluid intelligence and conscientiousness are the most important predictors of school grades. In addition to this main effect, researchers have suggested that the two traits might also interact with each other in the prediction of school success. A synergistic and a compensatory form of interaction have been suggested, but past evidence has been mixed so far. Most previous studies on this subject have been cross-sectional and many of them focused on older adolescents or adults in upper secondary school or university. We thus investigated the main and interaction effects of fluid intelligence and conscientiousness on school grades in math and German in a longitudinal sample of 1043 German students from age 11 to 15 years. Results from latent growth curve models with latent interaction terms showed a small compensatory interaction effect for baseline levels of math grades but not for their development. No interaction effect was found for German grades. These findings are discussed against the background that (synergistic) interaction effects between intelligence and conscientiousness might be more relevant in older students from higher secondary school or university context.

Does intelligence predict development of investment traits from mid to late adolescence? Evidence from a 3-year longitudinal study.

INTRODUCTION: Investment theories have claimed reciprocal relations between intelligence and investment traits (i.e., personality traits related to seeking out, and dealing with, cognitive challenges). However, previous research has primarily addressed the effects of investment traits on intellectual development (environmental enrichment hypothesis) and often focused on either childhood or later adulthood. The present study investigated the effects of intelligence on investment traits (environmental success hypothesis) from mid to late adolescence. METHOD: In a 3-year longitudinal survey (2008-2011) covering four measurement occasions, the predictive effects of both fluid and crystallized intelligence on intraindividual change in both the achievement motive (i.e., hope for success and fear of failure) and need for cognition were examined. Overall, 476 adolescents (t1 : Mage = 16.43, SD = 0.55; 51.3% girls) from Germany participated. RESULTS: Second-order latent growth models indicated that fluid intelligence predicted a steeper growth in hope for success (ß = .40), but was unrelated to change in the other investment traits. Crystallized intelligence had no effects on the investment traits under study. CONCLUSIONS: The results contribute to the research on the bidirectionality of intelligence and investment traits and add to our understanding of personality development from mid to late adolescence. Specifically, they underline the importance of nurturing hope for success especially in individuals with lower intelligence, but also show that support for the environmental success hypothesis seems to be limited to certain investment traits.

On the link of self-esteem, life satisfaction, and Neuroticism.

OBJECTIVE: Self-esteem (SE) and life satisfaction (LS) are highly correlated but little is known about the sources of this association. Both characteristic adaptations are negatively correlated with Neuroticism (N). We investigated the relationship between SE, LS, and N and the degree to which shared variance was explained by N from a behavior genetic perspective. METHOD: We analyzed more than 2,000 German same-sex twin pairs and their siblings. Twins were 17 and  23 years old and siblings were M = 21.6 years old. The sample was balanced regarding gender. We applied multivariate twin-sibling Cholesky models to obtain genetic and environmental correlations and estimated the impact N had on genetic and environmental correlations of SE and LS. RESULTS: The genetic correlation between SE and LS was .99 and 47% of this phenotypic correlation was explained by genetics. About 28% of the common genetic variance between SE and LS was explained by shared genes with N. CONCLUSIONS: Our findings suggest that N is not a common factor of SE and LS. The results are not in line with theories assuming that N is a basic tendency whose genetic factors account for most of the genetic variance between the assumed characteristic adaptations SE and LS.