Social relationships,stressful life events,and self-reported physical health: Genetic and environmental influences

Abstract

This study investigates how the associations between self-reported health, stressful life events, and social relationships are mediated by genetic and environmental influences and how much of the variance in health is in common with variation in these psychosocial factors. The analyses are based on questionnaire data from 576 pairs of twins reared apart and twins reared together. The data revealed that for men environmental influences were solely important for variation in the psychosocial measures and were the primary mediators of the relationship with health. For women, on the other hand, a substantial portion of the variance in the psychosocial factors was due to genetic influences and these influences also contributed to the bulk of the correlations with health. The gender differences for the relationships and their mediation indicate that what should be regarded as a psychosocial factor of importance for health might differ between genders.     

Examining the State-Trait Anxiety Relationship: A Behavioural Genetic Approach

State and trait anxiety define different aspects of anxiety, and may represent environmentally and genetically mediated components of this phenotype. Furthermore their relationship, where trait anxiety is expressed through levels of state anxiety under threatening circumstances, may represent a process of interplay between a genetic vulnerability factor and an environmental stressor. To test these hypotheses, we explored genetic and environmental influences on measures of state and trait anxiety in a sample of 1058 twins (521 males and 537 females) aged 8–16. The results were consistent with these hypotheses. State anxiety is largely influenced by environmental factors in males and females whereas trait anxiety shows moderate genetic effects and substantial non-shared environment effects. Their association was accounted for by non-shared environmental effects, with modest genetic and shared environmental inputs. The implications of these results for vulnerability mechanisms involving stress reactivity on anxiety are discussed.     

Ductile fracture mechanism in fine-grained magnesium alloy

The ductile fracture mechanism in a fine-grained magnesium alloy has been investigated by transmission electron microscopy-focused ion beam techniques. In coarse-grained or conventional magnesium alloys, twins form at the very beginning of the deformation process, and crack propagation occurs through the twin boundaries. However, in the alloy used in this study, subgrain structures were found instead of twins at the crack tip. Nanoscale twins formed subsequently owing to large stress in the crack propagation route. The fine-grained alloys showed high fracture toughness resulting from resistance to the twins at the beginning of the deformation.     

Patterns of Mother-Infant Contact: The Significance of Lateral Preference

The use of assisted reproductive technology is increasing rapidly. Research, although sparse, has resulted in inconsistent findings as to the developmental prognosis for infants conceived by assisted reproductive techniques such as in vitro fertilization and the use of fertility drugs. In the present study, the authors compared twins who were spontaneously conceived with those who were conceived through assisted reproductive technology. The authors found differences in birth weight and gestational age. Infants conceived by assisted reproductive technology fared worse than did those who were spontaneously conceived. The authors found no differences between the groups in mental development at 24 months of age, but they found evidence of differences in physical development. Implications of the findings are discussed.     

Syzygy: Love Made Strange

Abstract : This paper argues that there can be an intimate, non‐marital loving communion between two persons or, sometimes, two groups. The Christian tradition has its own concept, syzygy, for such love. An awareness of this forgotten tradition may be valuable in discussing some broader problems in the church, such as rivalry between different parties or homosexuality. The syzygic relationship of love and rivalry is characteristic of some well‐known biblical and mythological narratives.     

运动员心理选材的遗传学基础

采用文献综述法对心理指标的遗传问题做了研究,从而为运动员的心理选材提供遗传学的支撑。心理指标的遗传属于数量遗传,目前国内外的研究大都采用双生子之间相关的研究范式和收养子女与其生父母的相关以及其养父母的相关的研究范式,来估计心理指标的遗传度。大量的研究显示,人格的遗传度的范围为0.40~0.60;智力的遗传度在0.40~0.70之间,而其他心理指标的遗传度研究较少。在心理选材时,还应特别注意遗传因素与年龄的关系,因为遗传度随年龄的增长而发展变化。     

Infants’ sense of approximate numerosity: Heritability and link to other concurrent traits

The ability to perceive approximate numerosity is present in many animal species, and emerges early in human infants. Later in life, it is moderately heritable and associated with mathematical abilities, but the etiology of the Approximate Number System (ANS) and its degree of independence from other cognitive abilities in infancy is unknown. Here, we assessed the phenotypic specificity as well as the influence of genetic and environmental factors on the ANS in a sample of 5-month-old twins (N = 514). We found a small-to-moderate but statistically significant effect of genetic factors on ANS acuity (heritability = 0.18, 95% CI: 0.02, 0.33), but only when differences in numerosity were relatively large (1:4 ratio). Non-verbal ability assessed with the Mullen Scales of Early Learning (MSEL) was found to be heritable (0.47; 95% CI: 0.34, 0.57) and the phenotypic association between ANS acuity and non-verbal ability performance was close to zero. Similarly, we found no association between ANS acuity and general attention during the task. An unexpected weak but statistically significant negative association between ANS acuity and scores on the receptive language scale of the MSEL was found. These results suggest that early ANS function may be largely independent from other aspects of non-verbal development. Further, variability in ANS in infancy seems to, to some extent, reflect genotypic differences in the population.

Highlights

• Assessing 514 infant twins with eye tracking, we found that infants' sense of approximate numerosity is heritable and not positively associated with concurrent attentional, cognitive or motor abilities.
• These results have implications for our understanding of development of mathematical ability and the link between cognitive abilities early in postnatal life.