遗传、环境和青少年的吸烟饮酒行为：芬兰双生子研究的回溯与前瞻

本文介绍的两个“芬兰双生子（Finn Twin）”研究是对10个出生组的青少年双生子及其家庭的长期跟踪研究。本文概述了这两个项目对遗传与环境的关联和互动对吸烟饮酒行为影响的研究。这些研究的结果提示个体差异对吸烟饮酒行为的长期变动的影响受到兄弟姐妹互动、同伴互动以及父母教养方式的调节。环境对吸烟饮酒的影响主要表现在学校、居住社区与家庭环境的差异上。环境与遗传影响的程度和持久度有城乡差异。遗传的影响受居住社区的制约。多阶段模型的分析揭示了遗传与环境的互动对这些行为的演变（从试吸试饮到发展到滥用）的动态的影响,遗传似乎对吸烟饮酒的共同轨迹更有影响。这些结果对今后本项目对这约1万对芬兰成年双生子的分子遗传学研究提供了有益的线索     

EFFECTS OF AN ORAL HYGIENE PUNISHMENT PROCEDURE ON CHRONIC RUMINATION AND COLLATERAL BEHAVIORS IN MONOZYGOUS TWINS

This study investigated the suppressive effects of an oral hygiene punishment procedure on the ruminative behavior of profoundly retarded monozygous twins. Rumination, fingers in mouth/tongue out, appropriate behavior, and stereotyped behavior were measured before and during treatment with oral hygiene. Treatment was introduced for each meal in succession across the twins in a multiple-baseline design. Results showed that the rate of rumination of both twins was dramatically reduced to very low levels and stereotyped behavior increased spontaneously with the introduction of oral hygiene. Maintenance data showed that response reduction was maintained over a six-month period and, when compared to baseline levels, increased rates of socially appropriate behavior were evident in both children.     

Genetic and Environmental Influences on Personal and Rhythmic‐Motor‐Activity Tempo in Children: A Twin Study

In this study, we investigated the degree to which genetics and environmental factors influence the tempo and tempo stability of rhythmic motor activity in young children, using a twin study design. A total of 116 twin children, aged 4 years, were asked to strike two small clash cymbals together in a cyclical manner, in three phases. In the first phase, children were asked to maintain a comfortable personal tempo of rhythmic motor activity (spontaneous motor phase). In contrast, in the other phases, children were required to synchronize rhythmic motor activity in response to the timing of a stimulus tone, or a memorized tempo. Large additive genetic, although negligible shared environmental influences, were observed in the spontaneous motor phase. However, environmental factors were estimated in the other two phases, while the additive genetic factor was nearly zero. These results indicate that the extent of genetic and environmental influences on individual differences in rhythmic motor activity can be modulated under different situations.     

Social closeness of MZ and DZ twin parents towards nieces and nephews

Twins' marriages to non‐twins yield genetically and socially informative kinships. Monozygotic (MZ) twins' genetic identity makes them ‘genetic parents’ of their nieces/nephews, and their nieces/nephews their ‘genetic children’. The present study is the first to apply twin‐family models to study social relatedness. Analyses of twin families (MZ: N = 248; DZ: N = 75) tested evolutionary‐based concepts concerning social closeness, perceived similarity and caretaking. Hypotheses based on Hamilton's inclusive fitness theory were supported: MZ twin aunts/uncles expressed greater social closeness towards their nieces/nephews than DZ twin aunts/uncles; and female twins from same‐sex pairs expressed greater closeness towards their nieces/nephews than male twins from same‐sex pairs. This study underlines benefits of associations between behavioural‐genetic and evolutionary psychological theories, methods and interpretations. Copyright © 2007 John Wiley & Sons, Ltd.     

Genetic Influences on Anxiety in Children: What we’ve Learned and Where we’re Heading

Anxiety is a common problem, typically beginning early in life. This article explores reasons for individual differences in levels of anxiety among children, by reviewing the genetic literature. The plethora of research to date has demonstrated clearly that both genes and environmental influences play important roles in explaining differences in levels of anxiety of various types among children. This has encouraged researchers to search for specific genes and environmental influences upon anxiety. Despite important progress in identifying links between anxiety and specific genes—including associations between serotonin and dopamine genes and different symptoms of anxiety—overall, progress has been slow because multiple genes of small effect size are likely to influence anxiety. This article explains how the hunt for genes involved in anxiety is likely to benefit from genetically sensitive research, which examines the co-occurrence of symptoms; includes measures of the environment; and examines endophenotypes and risk pathways.     

The Recaptured Scale Technique: A Method for Testing the Structural Robustness of Personality Scales

Tellegen and Waller advocated a complex and time-consuming scale construction method that they called “exploratory test construction.” Scales that are constructed by this method—such as the Multidimensional Personality Questionnaire (MPQ)—are presumed to be more “psychologically coherent” and “robust” than scales constructed by other means. Using a novel procedure that we call the “recaptured scale technique,” we tested this conjecture by conducting a megafactor analysis on data from the 411 adult participants of the Minnesota Study of Twins Reared Apart who completed the MPQ, the MMPI, and the CPI. We extracted and obliquely rotated 21 factors from a matrix of gender-corrected tetrachoric correlations for the 1,102 nonredundant items of the three omnibus inventories. Robustness of the 11 MPQ scales was assessed by the degree to which these factors recaptured the MPQ item groupings. Our results showed that nine factors were clearly recognizable as MPQ scales and two additional factors represented a bifurcation of an MPQ scale. A higher-order factor analysis of all 21 factor scales yielded five factors that clearly resembled the Big Five. Our results provide strong support for (a) the method of exploratory test construction, (b) the structural robustness of most MPQ scales, and (c) the utility of the recaptured scale technique.     

Fracture mechanism of a coarse-grained magnesium alloy during fracture toughness testing

The fracture mechanism during fracture toughness testing has been investigated on a coarse-grained magnesium alloy, with an average grain size of ～50 µm, and a low fracture toughness. The results show that {1012}-type deformation twins are formed at the crack tip and many dislocations pile up on these boundaries. The accumulated strains at these boundaries become the origin of fracture; i.e. cracks propagate along these boundaries between the deformation twins and the matrix.     

Deformation twins induced by multi-mode deformation in nanocrystalline copper

A multi-mode deformation model is used in a molecular dynamics simulation of nanocrystalline copper. Abundant deformation twin lamellae are developed by shearing the following compression to the elastic limit. Deformation twins (DTs) nucleate through two different mechanisms facilitated by Shockley partial slips. Interactions between DTs and Shockley partials are observed in this simulation.     

Adam and Eve’s Origin: A Theory Harmonising Scientific Evidence with the Qur’anic Text1

A Muslim scientist engaged in interaction between theology and science needs to remain completely faithful to the Holy Qur’an. This also applies to understanding the historical and spiritual dimensions of Adam and Eve. When Islamic scholars (‘ulama’) differ on subject details, this author chooses the position closest to that suggested by the scientific data. This method, then, allows incorporation of facts drawn from skeletal material of early Homo sapiens who could well have provided our ancestral physical form. This article tenders a parsimonious and probable theory that accommodates all relevant Qur’anic statements in conjunction with the scientific data.     

Maternal speech style with prelinguistic twin infants

The mother–infant communicative speech of a group of mothers of 4‐month‐old first‐born twin infants was compared to the speech of a group of mothers of first‐born singleton infants. Maternal groups were matched on age, education level, mother–infant attachment status and infant gender, and maternal depression was assessed as a control variable. Maternal speech was coded for focus, content, complexity and syntax of mothers' utterances. The findings of earlier studies with toddler age twins, that maternal speech style was more directive and less infant‐focused, were replicated in this prelinguistic period of infancy. Compared to mothers of singletons, mothers of twins used less infant‐focused speech, were less responsive to their infants' cues, and attributed less agency to their infants. Mothers of twins also used fewer questions and requests but did not differ from mothers of singletons in their use of negatives and imperatives. These early differences in the language learning environments of twin and singleton infants may be due to the reduced opportunities that mothers of twins have to establish dyadic communicative routines with their infants and to familiarize themselves with their infants as interactive partners, and may have implications for the early language development of twins. Copyright © 2002 John Wiley & Sons, Ltd.