Using Genetically Informative Family Data to Examine the Early Development of Complex Traits

本项目对三个基因敏感的家庭设计——经典双胞胎研究、亲子收养研究和母子三胞胎的基因组分析——的证据进行了三角分析，以探索基因型、环境以及两者之间的相互作用在复杂性状发展中的作用。它使用这些设计来解决两个尚未解决的问题：(1)遗传和环境对心理、发展和学术特征的影响的最早表现是什么？(2)遗传对学业成绩的影响是否通过早期照料环境的诱发差异介导？这些问题在四个实证章节中进行了探讨：第一章系统地回顾和荟萃分析了关于遗传、共有和非共有环境对婴儿心理特征和发育里程碑的个体差异的影响的大型双胞胎研究文献。第二项研究考察了遗传对学业能力影响的最早表现，表明语言的变化可能是遗传对后来的学业表现影响的重要早期表现。第三章和第四章使用两种不同的遗传信息方法（收养设计和母亲-父亲-孩子三人组的基因组分析）研究了遗传影响对学习成绩的影响是否通过早期照顾环境的诱发差异来介导。其中一项研究发现，有证据表明，父母可能会根据孩子的教育相关遗传倾向来调整自己的育儿方式。这两项研究都没有发现父母教养会影响基因对学业成绩的影响，但他们都重复了语言会影响基因对学业成绩的影响这一发现，这表明早期语言可能是基因对后来学业成绩影响的早期标志。总的来说，这个项目提供了遗传和环境影响的早期表现，以及两者之间的相互作用，对复杂性状的个体差异的新信息。在这样做的过程中，它表明遗传敏感的基于家庭的研究不仅可以用来进一步了解遗传影响，还可以用来更好地理解复杂性状发展中的环境途径

This project triangulated evidence from three genetically sensitive family designs-classical twin studies, a parent-offspring adoption study, and genomic analysis of mother-father-child trios-to explore the roles of genotypes, environments, and interplay between the two, in the development of complex traits. It used these designs to address two unresolved questions: (1) What are the earliest manifestations of genetic and environmental influences on psychological, developmental, and academic traits? (2) Are the effects of genetic influences on academic outcomes environmentally mediated via evoked differences in the early caregiving environment? These questions were explored in four empirical chapters: The first systematically reviewed and meta-analysed the large twin study literature on genetic and shared and nonshared environmental influences on individual differences in psychological traits and developmental milestones in infancy. The second examined the earliest manifestations of genetic influences on academic abilities, demonstrating that variation in language may be an important early manifestation of genetic influences on later academic performance. The third and fourth chapters examined, using two different genetically informative methods (the adoption design and genomic analysis of mother-father-child trios), whether the effects of genetic influences on academic performance were mediated via evoked differences in the early caregiving environment. One, but not the other, found evidence that parents may adjust their parenting based on their children's education-associated genetic predispositions. Neither found evidence that parenting mediated genetic effects on academic performance, but they both replicated the finding that language mediates genetic effects on academic performance, suggesting that early language may be an early marker of genetic effects on later academic outcomes. Overall, this project provides new information about the earliest manifestations of genetic and environmental effects, and interplay between the two, on individual differences in complex traits. In doing so it demonstrates that genetically sensitive family-based research can be leveraged not only to further knowledge of genetic influences but also to better understand environmental pathways in complex trait development