Person-Specific Non-shared Environmental Influences in Intra-individual Variability: A Preliminary Case of Daily School Feelings in Monozygotic Twins

Abstract

Most behavioural genetic studies focus on genetic and environmental influences on inter-individual phenotypic differences at the population level. The growing collection of intensive longitudinal data in social and behavioural science offers a unique opportunity to examine genetic and environmental influences on intra-individual phenotypic variability at the individual level. The current study introduces a novel idiographic approach and one novel method to investigate genetic and environmental influences on intra-individual variability by a simple empirical demonstration. Person-specific non-shared environmental influences on intra-individual variability of daily school feelings were estimated using time series data from twenty-one pairs of monozygotic twins (age = 10 years, 16 female pairs) over two consecutive weeks. Results showed substantial inter-individual heterogeneity in person-specific non-shared environmental influences. The current study represents a first step in investigating environmental influences on intra-individual variability with an idiographic approach, and provides implications for future behavioural genetic studies to examine developmental processes from a microscopic angle.

Family socioeconomic status amplifies unique environmental influences on the dynamics of adolescent daily positive affective process

“…Adolescents' affects are naturally impacted by these daily events and go up and down consequently as these events come and go. It is, thus, not surprising that η is predominantly explained by non‐shared environment: daily events are largely idiosyncratic and unique to each person (Burt et al., 2015; Zheng & Asbury, 2019; Zheng, Molenaar, et al., 2016). As opposed to these uncontrollable daily events, however, when facing environmental experiences that change our affect, what people can control more proactively is how quickly or gradually their affect returns to the equilibrium following any disturbance.…”

“…Particularly, our study is the largest regarding the sample size and time length of all twin studies with similar designs. Moreover, among extant scant twin studies using genetically informative intensive longitudinal data, few have examined affective dynamics in children and adolescents (Burt et al., 2015; Zheng, Molenaar, et al., 2016), while the majority focused on adults (Jacobs et al., 2006, 2013). Nonetheless, our sample size is admittedly smaller compared to other conventional twin studies.…”

“…Furthermore, adolescents show larger variations in their damping mechanisms such that their affects show various rates of returning to the equilibrium. Applying quantitative genetic methods to genetically informative intensive longitudinal data provides a unique opportunity to elucidate genetic and environmental origins of individual differences in temporal affective dynamics (Zheng, Molenaar, et al, 2016). Interestingly, positive and negative affect demonstrate similar patterns regarding their genetic and environmental contributions to individual differences in temporal affective dynamics.…”

Multilevel Dynamic Twin Modeling

“…By inspecting the results across the different twin pairs, the iFACE model can be used to get an impression of the differences between twin pairs in the processes and heritabilities when the iFACE model. For example, Zheng et al (2016) applied the iFACE model separately to the daily positive and negative school feelings of multiple 10-year-old MZ twin pairs. They found that the amount of variance in the daily fluctuations in these feelings that was due to unique environmental influences varied greatly across twin pairs.…”