Do Non-shared Environmental Influences Persist Over Time? An Examination of Days and Minutes

Abstract

Non-shared environmental influences show only minimal stability over time prior to adulthood. The long assessment lags (typically 3-5 years) that characterize most longitudinal twin studies, however, make it difficult to interpret these results. To more rigorously evaluate non-shared environmental stability prior to adulthood, we fitted biometric correlated factors models to 1) seven consecutive days of self-reported negative and positive affect in 239 twin pairs aged 16-25 years and 2) seven consecutive minutes of observer rated warmth and control in 687 twin pairs aged 6-10 years. We then empirically examined patterns of etiologic stability over time using a mixed effects analog to the one-way ANOVA. Genetic and shared environmental correlations were found to be highly stable over both days and minutes. By contrast, non-shared environmental correlations decreased monotonically with increasing lag length, and moreover, were small-to moderate in magnitude when examining intervals longer than a few minutes. Such findings imply that the non-shared environment may be comprised primarily of transient and idiosyncratic effects prior to adulthood.

Etiological influences on the stability of autistic traits from childhood to early adulthood: evidence from a twin study

“…This is potentially surprising given that nonshared environmental factors seldom appear to have an enduring effect on behavioral phenotypes across development [48]. It is worth arguing, however, that the nonshared environmental factors linked with autistic traits have largely included perinatal and prenatal factors [49, 50].…”

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

“…Specifically, group-level results showed substantial non-shared environmental influences for positive school feelings (73 %), but modest non-shared environmental influences for negative school feelings (16 %). The nonshared environmental factor had a low stability (r * .30) over 1 day lag, suggesting that it changed substantially across days and may consist primarily of idiosyncratic and transient experiences (Burt et al 2015).…”

“…How do results of genetic and environmental influences on intra-individual variability compare to results of genetic and environmental influences on inter-individual differences, or inter-individual differences in intra-individual changes that typically are examined in conventional behavioural genetic studies? The few existing empirical studies that have collected genetically informative ILD did not specifically examined genetic and environmental influences on intra-individual variability (e.g., Asbury et al 2008;Burt et al 2015;Cleveland and Almeida 2013;Jacobs et al 2006Jacobs et al , 2013Menne-Lothmann et al 2012;Neiss and Almeida 2004;Wichers et al 2007), and thus could not shed light on these questions.…”

“…As mentioned earlier, the few existing empirical studies that have collected genetically informative ILD on mood did not specifically examined genetic and environmental influences on intra-individual variability, but focused instead on inter-individual differences in constructs aggregated together over multiple observations, such as intra-individual mean and variation (e.g., Jacobs et al 2006Jacobs et al , 2013Menne-Lothmann et al 2012;Neiss and Almeida 2004;Wichers et al 2007). Among those studies, however, one study that followed 239 female twin pairs aged 16-25 years over a 7-day period provided some interesting results that could shed some lights on genetic and environmental influences on intra-individual variability of affect (Burt et al 2015). Besides the finding that both positive and negative affect were primarily explained by genetic (25-47 %) and non-shared environmental influences (54-75 %), it was also found that genetic stability remained high across days (*.95), whereas the stability of non-shared environmental influences was low and decreased monotonically with increasing time intervals (Burt et al 2015).…”

“…Among those studies, however, one study that followed 239 female twin pairs aged 16-25 years over a 7-day period provided some interesting results that could shed some lights on genetic and environmental influences on intra-individual variability of affect (Burt et al 2015). Besides the finding that both positive and negative affect were primarily explained by genetic (25-47 %) and non-shared environmental influences (54-75 %), it was also found that genetic stability remained high across days (*.95), whereas the stability of non-shared environmental influences was low and decreased monotonically with increasing time intervals (Burt et al 2015). This finding suggests that non-shared environmental influences could consist primarily of idiosyncratic and transient daily experience, and highlights the importance of examining intra-individual processes, particularly with regard to mood.…”