Department of Psychology, University of Amsterdam, Roetersstraat 15, 1018 WB, Amsterdam, The Netherlands.
Dev Sci. 2010 Jan 1;13(1):11-27. doi: 10.1111/j.1467-7687.2009.00858.x.
We present a review of empirical evidence that suggests that a substantial portion of phenotypic variance is due to nonlinear (epigenetic) processes during ontogenesis. The role of such processes as a source of phenotypic variance in human behaviour genetic studies is not fully appreciated. In addition to our review, we present simulation studies of nonlinear epigenetic variance using a computational model of neuronal network development. In each simulation study, time series for monozygotic and dizygotic twins were generated and analysed using conventional behaviour genetic modelling. In the results of these analyses, the nonlinear epigenetic variance was subsumed under the non-shared environmental component. As is commonly found in behaviour genetic studies, observed heritabilities and unique environmentabilities increased with time, whereas common environmentabilities decreased. The fact that the phenotypic effects of nonlinear epigenetic processes appear as unsystematic variance in conventional twin analyses complicates the identification and quantification of the ultimate genetic and environmental causes of individual differences. We believe that nonlinear dynamical system theories provide a challenging perspective on the development of individual differences, which may enrich behaviour genetic studies.
我们回顾了一些经验证据，这些证据表明，表型方差的很大一部分是由于个体发生过程中的非线性（表观遗传）过程。在人类行为遗传学研究中，这种过程作为表型方差的来源的作用尚未得到充分认识。除了我们的综述，我们还使用神经元网络发育的计算模型对非线性表观遗传方差进行了模拟研究。在每次模拟研究中，我们生成同卵双胞胎和异卵双胞胎的时间序列，并使用传统的行为遗传模型进行分析。在这些分析的结果中，非线性表观遗传方差被归入非共享环境成分之下。正如在行为遗传学研究中常见的那样，观察到的遗传力和独特环境能力随着时间的推移而增加，而共同环境能力则下降。非线性表观遗传过程的表型效应在传统的双胞胎分析中表现为非系统性方差，这使得确定和量化个体差异的最终遗传和环境原因变得复杂。我们认为，非线性动力系统理论为个体差异的发展提供了一个富有挑战性的视角，这可能会丰富行为遗传学研究。
