Bielefeld University, Germany.
Br J Educ Psychol. 2022 Sep;92(3):881-897. doi: 10.1111/bjep.12478. Epub 2021 Dec 10.
Educational attainment is connected to many important life outcomes, and the previous research has already focused on identifying its genetic and environmental components. However, most of these studies used twin data only and did not incorporate information from other family members. Twin studies typically decompose the phenotypic variance into genetic, shared, and unique environment components. In this study design, the shared environment component encompasses the influence of parents and the shared environments of twins and siblings independent of parents (e.g., teachers, schools, and peers). The classical twin design (CTD) conflates these influences as part of the shared environment. This shortcoming can be overcome using the nuclear twin family design (NTFD), which enables separation of the parental and shared twin/sibling environmental components.
The aim of this study was to broaden the understanding of the aetiology of educational attainment using the nuclear twin family design to provide a detailed account of the genetic and environmental effects on the type of school leaving certificate.
The data of 1,048 monozygotic and 916 dizygotic same-sex twins, their biological parents, and non-twin full biological siblings of the German project TwinLife were used in the nuclear twin family design.
Structural equation modelling (SEM) techniques were used to analyse the variance-covariance patterns of the ordinal outcome variable.
Genetic influences were found to make up around 60% of variance, whilst environmental influences shared by all siblings, educational influences shared by the twins only, and non-shared environmental influences explained the remaining variance in equal amounts. Environmental transmission from parent to offspring was found to be negligible.
Through its advanced design, our study extends the previous work enabling more detailed and robust estimations of sources of variance and contributes to a better understanding of the complex aetiology of educational attainment.
教育程度与许多重要的生活成果相关，先前的研究已经集中在确定其遗传和环境因素上。然而，这些研究大多仅使用双胞胎数据，并未纳入其他家庭成员的信息。双胞胎研究通常将表型方差分解为遗传、共享和独特环境成分。在这种研究设计中，共享环境成分包括父母的影响以及双胞胎和兄弟姐妹的独立于父母的共享环境（例如，教师、学校和同伴）的影响。经典的双胞胎设计（CTD）将这些影响混为共享环境的一部分。使用核双胞胎家庭设计（NTFD）可以克服这一缺点，该设计能够分离父母和共享双胞胎/兄弟姐妹的环境成分。
本研究旨在使用核双胞胎家庭设计拓宽对教育程度病因学的理解，详细说明遗传和环境因素对离校证书类型的影响。
德国双胞胎生活项目的数据包括 1048 对同卵双胞胎和 916 对异卵双胞胎及其生物学父母，以及非双胞胎全生物学兄弟姐妹。
使用结构方程模型（SEM）技术分析有序结果变量的方差协方差模式。
遗传影响约占 60%的方差，而所有兄弟姐妹共享的环境影响、仅双胞胎共享的教育影响以及非共享环境影响等量解释了剩余的方差。发现父母向子女传递环境影响可以忽略不计。
通过其先进的设计，我们的研究扩展了先前的工作，能够更详细和稳健地估计方差源，并有助于更好地理解教育程度复杂的病因学。
