How People Make Their Own Environments: A Theory of Genotype --> Environment Effects

Abstract

We propose a theory of development in which experience is directed by genotypes. Genotypic differences are proposed to affect phenotypic differences, both directly and through experience, via 3 kinds of genotype leads to environment effects: a passive kind, through environments provided by biologically related parents; an evocative kind, through responses elicited by individuals from others; and an active kind, through the selection of different environments by different people. The theory adapts the 3 kinds of genotype-environment correlations proposed by Plomin, DeFries, and Loehlin in a developmental model that is used to explain results from studies of deprivation, intervention, twins, and families.

Infant viewing of social scenes is under genetic control and is atypical in autism

“…Taken as a whole, these findings lend insight into the means by which phenotypic differences emerge from the interaction between individual genotypes and individually-experienced environments, theorized decades ago as the means by which children 'make their own environments' 7 via developmental successions of reliable and repeated couplings between organism and environment 29 . Similar notions have been advanced in phenotypic studies contrasting the experiential development of children with autism and their typically-developing peers 30 , yet never heretofore demonstrated as having directly traceable genetic influence.…”

“…Moreover, the measures that are most highly heritable, preferential attention to eye and mouth regions of the face, are also those that are differentially diminished in children with autism ( Χ 2 =64.03, P <0.0001). These results—which implicate social visual engagement as a neurodevelopmental endophenotype—not only for autism, but for population-wide variation in social-information-seeking 8 —reveal a means of human biological niche construction, with phenotypic differences emerging from the interaction of individual genotypes with early life experience 7 . …”

“…This capacity—social visual engagement—shapes typical infant development from birth 5 and is pathognomonically impaired in children affected by autism 6 . Here we show that variation in viewing of social scenes—including levels of preferential attention and the timing, direction, and targeting of individual eye movements—is strongly influenced by genetic factors, with effects directly traceable to the active seeking of social information 7 . In a series of eye-tracking experiments conducted with 338 toddlers—including 166 epidemiologically-ascertained twins, 88 non-twins with autism, and 84 singleton controls—we find high monozygotic twin-twin concordance (0.91) and relatively low dizygotic concordance (0.35).…”

“…These high levels of MZ concordance, observed at both macro- and micro-levels, indicate strong biological basis for variation in social visual engagement 7 , with a substantial portion of that variation attributable to additive genetic influence. While concordance in micro-level measures was more modest than macro, even modest micro-level concordance marks repeatable shifts in probability: repetition of these shifts—recurring as frequently as every 400–500msec—suggests a striking means by which small probabilistic differences might amount, developmentally, to large eventual effects.…”

“…For the second and third tests, analyses were restricted to measures made only when each twin watched different videos or different content categories of video; the null hypothesis held that concordance would be zero (ICC differentVideos =0 and ICC differentContent =0), the alternative stated that concordance would be greater than zero (ICC differentVideos >0 and ICC differentContent >0). Greater-than-zero concordance when each twin watched different videos or different content categories would evidence goal-directed action, less dependent on the exact stimulus (flexibly seeking social information as a form of active niche-picking 7 ). For each test, we measured levels of eye-looking and quantified physical image properties of all eyes stimuli 28 (Extended Data Figure 7).…”