scholarly journals Methylation as an epigenetic source of random genetic effects in the classical twin design

2015 ◽  
pp. 305 ◽  
Author(s):  
Dorret Boomsma ◽  
Conor Dolan ◽  
Michel Nivard ◽  
Jenny van Dongen ◽  
Sophia van der Sluis
Keyword(s):  
Genetic Effects ◽  
Twin Design ◽  
Classical Twin Design

scholarly journals Genomics of ageing in twins

2014 ◽  
Vol 73 (4) ◽  
pp. 526-531 ◽  
Author(s):  
Massimo Mangino
Keyword(s):  
Molecular Mechanisms ◽  
Twin Studies ◽  
Later Life ◽  
Twin Design ◽  
The Past ◽  
Human Ageing ◽  
Classical Twin Design ◽  
Environmental Component ◽  
Early Life Events ◽  
Generation Sequencing

Ageing is a complex multifactorial process, reflecting the progression of all degenerative pathways within an organism. Due to the increase of life expectancy, in recent years, there is a pressing need to identify early-life events and risk factors that determine health outcomes in later life. So far, genetic variation only explains ~20–25 % of the variability of human survival to age 80+. This clearly implies that other factors (environmental, epigenetic and lifestyle) contribute to lifespan and the rate of healthy ageing within an individual. Twin studies in the past two decades proved to be a very powerful tool to discriminate the genetic from the environmental component. The aim of this review is to describe the basic concepts of the twin study design and to report some of the latest studies in which high-throughput technologies (e.g. genome/epigenome-wide assay, next generation sequencing, MS metabolic profiling) combined with the classical twin design have been applied to the analysis of novel ‘omics’ to further understand the molecular mechanisms of human ageing.

Classical twin design in modern pharmacogenomics studies

2010 ◽  
Vol 11 (2) ◽  
pp. 215-226 ◽  
Author(s):  
Nilüfer Rahmioğlu ◽  
Kourosh R Ahmadi
Keyword(s):  
Twin Design ◽  
Classical Twin Design

scholarly journals Gene-Environment Interplay in Twin Models

2013 ◽  
Vol 21 (3) ◽  
pp. 368-389 ◽  
Author(s):  
Brad Verhulst ◽  
Peter K. Hatemi
Keyword(s):  
Genetic Similarity ◽  
Behavior Genetics ◽  
Empirical Studies ◽  
Environment Interaction ◽  
Twin Design ◽  
Gene Environment Interaction ◽  
Twin Model ◽  
Gene Environment ◽  
Twin Models ◽  
Classical Twin Design

In this article, we respond to Shultziner's critique that argues that identical twins are more alike not because of genetic similarity, but because they select into more similar environments and respond to stimuli in comparable ways, and that these effects bias twin model estimates to such an extent that they are invalid. The essay further argues that the theory and methods that undergird twin models, as well as the empirical studies which rely upon them, are unaware of these potential biases. We correct this and other misunderstandings in the essay and find that gene-environment (GE) interplay is a well-articulated concept in behavior genetics and political science, operationalized as gene-environment correlation and gene-environment interaction. Both are incorporated into interpretations of the classical twin design (CTD) and estimated in numerous empirical studies through extensions of the CTD. We then conduct simulations to quantify the influence of GE interplay on estimates from the CTD. Due to the criticism's mischaracterization of the CTD and GE interplay, combined with the absence of any empirical evidence to counter what is presented in the extant literature and this article, we conclude that the critique does not enhance our understanding of the processes that drive political traits, genetic or otherwise.

Choosing sides: The genetics of why we go with the loudest

2012 ◽  
Vol 24 (3) ◽  
pp. 389-408 ◽  
Author(s):  
Zoltán Fazekas ◽  
Levente Littvay
Keyword(s):  
Individual Differences ◽  
Party Identification ◽  
Decision Strategy ◽  
Twin Design ◽  
Spatial Voting ◽  
Recent Developments ◽  
Classical Twin Design ◽  
Voter Models ◽  
Rational Voter ◽  
The Individual

Recent developments in spatial voting have moved beyond finding the most appropriate utility function and started to assess individual differences in decision strategy. The question is not if a proximity or directional worldview performs better in general, rather under what conditions do people pick one strategy over the other? We draw on psychological theories to develop a survey-based measure of individual decision strategy and take a behavior genetic route to explaining the individual differences. We argue that dispositional traits shape whether an individual develops a directional or proximity worldview of the political arena. Utilizing a classical twin design, we capitalize on the documented relationship between partisanship and a directionalist worldview. We find that, in the Minnesota Twin Political Survey, both the strength of party identification and directional voting are moderately (~20 percent) but significantly ( p < 0.05) heritable with no socialized component contributing to the variance. The covariation between the two traits is predominantly driven by common underlying genetic effects ( p < 0.01). Implications for the rational voter models are discussed in light of the findings.

scholarly journals Heritability in friendship networks

2020 ◽  
Author(s):  
Michael Neugart ◽  
Selen Yildirim
Keyword(s):  
Friendship Networks ◽  
Economic Success ◽  
Twin Design ◽  
Network Characteristics ◽  
Classical Twin Design ◽  
Using Data

AbstractFriendship networks account for a large part of an individual’s economic success or failure in life. Using data from the German TwinLife study, we explore, within a classical twin design, to which extent friendship networks are related to genes. We find a substantial heritability component in twins’ network sizes and network homophily, but not in twins’ network closeness. Addressing indirect ways in which genes could influence network characteristics, we do not find evidence that shared hobbies affects networks.

scholarly journals Extending Causality Tests with Genetic Instruments: An Integration of Mendelian Randomization with the Classical Twin Design

2018 ◽  
Vol 48 (4) ◽  
pp. 337-349 ◽  
Author(s):  
Camelia C. Minică ◽  
Conor V. Dolan ◽  
Dorret I. Boomsma ◽  
Eco de Geus ◽  
Michael C. Neale
Keyword(s):  
Mendelian Randomization ◽  
Twin Design ◽  
Causality Tests ◽  
Classical Twin Design ◽  
Genetic Instruments

scholarly journals Using Non-Normal SEM to Resolve the ACDE Model in the Classical Twin Design

2010 ◽  
Vol 41 (2) ◽  
pp. 329-339 ◽  
Author(s):  
Koken Ozaki ◽  
Hideki Toyoda ◽  
Norikazu Iwama ◽  
Saori Kubo ◽  
Juko Ando
Keyword(s):  
Twin Design ◽  
Classical Twin Design

Effects of Chorion Type on Genetic and Environmental Influences on Height, Weight, and Body Mass Index in South Korean Young Twins

2008 ◽  
Vol 11 (1) ◽  
pp. 63-69 ◽  
Author(s):  
Yoon-Mi Hur ◽  
Jung-Sik Shin
Keyword(s):  
Body Mass Index ◽  
Maximum Likelihood ◽  
Body Mass ◽  
Statistical Significance ◽  
Environmental Influences ◽  
Model Fitting ◽  
Twin Design ◽  
South Korean ◽  
Classical Twin Design ◽  
Chorion Type

AbstractThe present study examined the effects of chorionicity of twins on variations of height, weight, and body mass index (BMI) during childhood in the classical twin design. Mothers of 81 pairs of monochorionic monozygotic (MCMZ), 47 pairs of dichorionic monozygotic (DCMZ), and 457 pairs of dizygotic (DZ) twins drawn from the South Korean Twin Registry reported their children's height and weight. Twins' age ranged from 1.9 to 8.7 yrs, with a mean of 4.0 yrs and SD of 1.7 yrs. We computed maximum likelihood twin correlations and performed model-fitting analyses. In correlational and model-fitting analyses, we treated age and sex as covariates to control their main effects. Maximum likelihood MCMZ, DCMZ, and DZ twin correlations were, respectively, .96, .92, and .74, for height, .88, .91, and .57 for weight, and .93, .92, and .61 for BMI. The pattern of these twin correlations suggested very modest chorion effects on body measures. Model-fitting analyses confirmed the observations from twin correlations. Whereas genetic and shared environmental influences were significant for all three body measures, chorion effects attained statistical significance only for height (4%), and those for weight and BMI were zero. These findings indicate that genetic and environmental estimates for height, weight, and BMI during childhood are biased little by the chorion type of MZ twins, supporting the validity of the equal prenatal environment assumption in the classical twin design.

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