Suchergebnisse

AbstractWhile heritability studies show that most of the variance in adult personality can be attributed to genetic or so-called nonshared environmental influence, this does not mean that shared events lack importance for the development of later personality differences. We studied the relationship between Big Five personality differences in monozygotic (MZ) twins at age 29, and life stressors at age 6 to 15, using prospective data from 26 MZ pairs studied from birth onwards. A positive significant correlation was found between stressors in childhood and early adolescence, and intrapair personality differences in Agreeableness, Openness, Conscientiousness, and five-factor profiles. We note that the effects of shared events are labeled "nonshared" environment when the effect is to make siblings more different. Case examples illustrate the relationship between stress and personality differences, and provide hypotheses for further studies in larger samples.

In an era of expanding interest in international environmental problems,1 it is essential to examine the rapidly developing state practice concerning man's startling capability, through the use of technology without any hostile intent, adversely to alter not just the immediate environment of his neighbor but common resources shared by all. The present discussion does not attempt to deal with the practice of all states, but rather considers the extent to which legally relevant expectations of restraint, are being shaped by United States practice concerning the use of novel technology in the res communis? The focus on United States practice reflects the belief that, within the confines of a law journal article, considerable light may be shed on world community expectations by an examination of the practice of a state which has a major interest in the field and which
is a significant participant in the international law-creating process.

The division of Germany into two militarized blocs during the Cold War fundamentally shaped the lives of people living in both East and West. Yet, as recent scholarship has increasingly highlighted, there were also numerous areas of contact and interaction, whether in the cultural, political or social sphere. One largely overlooked aspect of these Cold War relations, which this article explores, is the environment. Focusing on the history of the shared German environment from the end of the Second World War through to the early 1970s, the article argues that on a local level, environmental problems helped to ensure the survival of cross-border relations. Despite their repeated efforts, the two states failed to divide the German landscape in half. Rivers, lakes and forests continually crossed the fortified border, while animals and plant life traversed from one side to the other too. In attempting to maintain this shared border landscape, East and West Germans were repeatedly forced into dialogue. Although relations gradually faded as the border regime was strengthened, it proved impossible for either side to escape fully the entangled German environment.

AbstractMetabolites are small molecules involved in cellular metabolism where they act as reaction substrates or products. The term 'metabolomics' refers to the comprehensive study of these molecules. The concentrations of metabolites in biological tissues are under genetic control, but this is limited by environmental factors such as diet. In adult mono- and dizygotic twin pairs, we estimated the contribution of genetic and shared environmental influences on metabolite levels by structural equation modeling and tested whether the familial resemblance for metabolite levels is mainly explained by genetic or by environmental factors that are shared by family members. Metabolites were measured across three platforms: two based on proton nuclear magnetic resonance techniques and one employing mass spectrometry. These three platforms comprised 237 single metabolic traits of several chemical classes. For the three platforms, metabolites were assessed in 1407, 1037 and 1116 twin pairs, respectively. We carried out power calculations to establish what percentage of shared environmental variance could be detected given these sample sizes. Our study did not find evidence for a systematic contribution of shared environment, defined as the influence of growing up together in the same household, on metabolites assessed in adulthood. Significant heritability was observed for nearly all 237 metabolites; significant contribution of the shared environment was limited to 6 metabolites. The top quartile of the heritability distribution was populated by 5 of the 11 investigated chemical classes. In this quartile, metabolites of the class lipoprotein were significantly overrepresented, whereas metabolites of classes glycerophospholipids and glycerolipids were significantly underrepresented.

AbstractBehavioral and molecular genetic research has established that child cognitive ability and academic performance are substantially heritable, but genetic variation does not account for all of the stratification of cognitive and academic outcomes across families. Which specific contexts and experiences contribute to these shared environmental influences on cognitive ability and academic achievement? Using an ethnically and socioeconomically diverse sample of N = 1728 twins ages 7–20 from the Texas Twin Project, we identified specific measured family, school, and neighborhood socioecological contexts that statistically accounted for latent shared environmental variance in cognitive abilities and academic skills. Composite measures of parent socioeconomic status (SES), school demographic composition, and neighborhood SES accounted for moderate proportions of variation in IQ and achievement. Total variance explained by the multilevel contexts ranged from 15% to 22%. The influence of family SES on IQ and achievement overlapped substantially with the influence of school and neighborhood predictors. Together with race, the measured socioecological contexts explained 100% of shared environmental influences on IQ and approximately 79% of shared environmental influences on both verbal comprehension and reading ability. In contrast, nontrivial proportions of shared environmental variation in math performance were left unexplained. We highlight the potential utility of constructing "polyenvironmental risk scores" in an effort to better predict developmental outcomes and to quantify children's and adolescents' interrelated networks of experiences. A video abstract of this article can be viewed at: https://youtu.be/77E_DctFsr0

Perceived‐control 'describes individuals'generalized beliefs about their abilities to influence their life courses and circumstances. Most research concerning this construct has viewed perceived control as a developmentally acquired, stable personality characteristic. Others argue that perceived control is determined by current social status, with more privileged social positions contributing to increased control over life circumstances.This study analyzes data from the Virginia Twin Registry to determine the independent contributions of genetics, shared environment, and nonshared environment, including adult roles and statuses, on women's perceived control. Findings from latent variable twin models suggest that there are modest but significant effects of shared environment and genetics on perceived control but that the majority of individual variation in perceived control is due to nonshared environmental factors on perceived control among adult women. Analyses of measured individual‐level variables indicate significant effects from education, income, earnings, marital quality, age, and single‐parent status.

Abstract
Stochastic multiplicative dynamics characterize many complex natural phenomena such as selection and mutation in evolving populations, and the generation and distribution of wealth within social systems. Population heterogeneity in stochastic growth rates has been shown to be the critical driver of wealth inequality over long time scales. However, we still lack a general statistical theory that systematically explains the origins of these heterogeneities resulting from the dynamical adaptation of agents to their environment. In this paper, we derive population growth parameters resulting from the general interaction between agents and their environment, conditional on subjective signals each agent perceives. We show that average wealth-growth rates converge, under specific conditions, to their maximal value as the mutual information between the agent's signal and the environment, and that sequential Bayesian inference is the optimal strategy for reaching this maximum. It follows that when all agents access the same statistical environment, the learning process attenuates growth rate disparities, reducing the long-term effects of heterogeneity on inequality. Our approach shows how the formal properties of information underlie general growth dynamics across social and biological phenomena, including cooperation and the effects of education and learning on life history choices.