Department of Psychology, Bielefeld University, Bielefeld, Germany.
PLoS One. 2020 Mar 23;15(3):e0230626. doi: 10.1371/journal.pone.0230626. eCollection 2020.
Internalizing and externalizing behavior problems are established risk factors for many unpleasant outcomes and psychopathology in adulthood, and understanding the interplay between genes and environment is important for deducing implications for therapeutic interventions. Among genetic studies on internalizing and externalizing problem behavior, the heritability estimates differ widely. Most research only uses twin data and other-reports, and therefore certain limitations are inevitable. Our study is the first to investigate genetic and environmental influences on problem behavior using a Nuclear Twin Family Design and self-reports, in order to address these limitations. Internalizing and externalizing problem behavior of 3,087 twin pairs (age 11-23), a sibling, and their parents were analyzed with structural equation modeling to estimate heritability separately for each of three twin birth cohorts. Genetic influences account for about one-third of the variance for both internalizing and externalizing. Shared environmental influences were only found for internalizing, and through the advantages of considering data from the whole twin family, firstly could be identified as solely twin-specific. Our findings could contribute to a better understanding of the gap between heritability based on twin studies and DNA-based heritability ('missing heritability problem'): Results indicate that heritability estimates gained via classic twin design and other-reports are slightly overestimated and therefore environmental influences, in general, are more important than previous research suggests. Simultaneously, we showed that family-specific environment either contributes to behavior problems only on an individual level, or that it has a lesser influence than originally thought.
内化和外化行为问题是成年后许多不愉快结果和精神病理学的既定风险因素，了解基因和环境之间的相互作用对于推断治疗干预的意义很重要。在关于内化和外化问题行为的遗传研究中，遗传率的估计差异很大。大多数研究仅使用双胞胎数据和他人报告，因此不可避免地存在某些局限性。我们的研究首次使用核双胞胎家庭设计和自我报告来调查问题行为的遗传和环境影响，以解决这些局限性。使用结构方程模型对 3087 对双胞胎（年龄 11-23 岁）、兄弟姐妹及其父母的内化和外化问题行为进行了分析，以分别估计三个双胞胎出生队列中每种行为的遗传率。遗传影响约占内化和外化的三分之一。仅发现共享环境影响与内化有关，并且通过考虑整个双胞胎家庭数据的优势，可以首先将其识别为仅双胞胎特异性。我们的研究结果有助于更好地理解基于双胞胎研究的遗传率与基于 DNA 的遗传率之间的差距（“遗传缺失问题”）：结果表明，通过经典双胞胎设计和他人报告获得的遗传率估计值被略微高估，因此环境影响通常比以前的研究表明的更为重要。同时，我们表明，家庭特定环境要么仅在个体水平上对行为问题有贡献，要么其影响比最初认为的要小。
