Consistent with previous studies using parental reports, we confirmed that children's experience of household chaos was associated with how well they performed in school. The more disorganized, noisy and confusing children perceived their homes to be, the poorer their performance in school. Environmental factors that make siblings more alike – shared environments – explained the largest part of the chaos–school achievement relationship. This might be expected considering chaos is after all a measure of the home environment, but noteworthy nonetheless given the recent rethinking about the effects of the shared environment (Burt, 2009
). Remarkably, however, over a third of the association between children's perceptions of family chaos and their teacher-rated achievement was accounted for by common genetic factors.
Environmental confusion at home predicts poor performance in school
Using a genetically sensitive design made it possible to characterize the influence of home environment on school achievement. By controlling for genetic effects, we have shown that about two-thirds of the association between chaos and school achievement is because of shared environmental factors. What could these shared experiences be? Obvious candidates are the elements of the scale itself, such as the items ‘I have a regular bedtime routine’, and ‘There is usually a television turned on somewhere in our home’. A previous study has found that the elements of the household chaos scale that tap order and routine (as opposed to noise) predict early reading skill (Johnson et al., 2008
). This is supported by evidence that children living in unstable chaotic homes withdraw from academic challenge – an effect partially mediated by disrupted and inconsistent sleep patterns (Brown & Low, 2008
). Poor ‘sleep hygiene’– irregular sleeping patterns including difficulty getting to sleep, staying asleep and excessive tiredness – is predictive of poor school performance (Bruni et al., 2006
). Another characteristic of the chaotic home, immoderate television watching, both directly predict poor school performance and is significantly associated with disrupted sleep patterns (Li et al., 2007
; Sharif & Sargent, 2010
; Van Den Bulck, 2004
). Of course, all these ‘environments’ are components of the heritable CHAOS scale, and are therefore likely themselves to be partly genetic in origin.
Genetically driven experience: G → E correlation
The surprising finding here, however, is that the association between chaos and school achievement is not entirely environmental in origin. A common set of genetic factors explains a third of the association between the children's heritable experience of household chaos and their school achievement. But whose genes explain this relationship: the parents’ or the child's? If parents who create chaotic home environments also do not encourage schoolwork or take an interest in homework because of their genetic predisposition, the GE correlation between home and school is passive; parental genes bridge the children's experience of environmental confusion at home and their school performance. That is to say, children get their genes as well as their genetically influenced environment from their parents.
However, passive GE correlation on its own is only one step removed from a scenario in which the child, a blank slate, is entirely at the mercy of their nurture. Given that by the age of 12 we might expect that children are having some input into their routine at home and commitment to school, it seems likely that the genetic link between home and school is at least in part due to the child's genes: an active (or reactive) child-driven process. For example, if children are particularly uncooperative about going to bed, turning off the television or sitting down to meals, their parents may abandon attempts to impose structure on their environment. Similarly, the children's teachers may have to spend more time managing the children's behaviour than teaching them. Modifying the child's behaviour might allow parents to successfully implement regular routines and allow teachers to more effectively educate the child.
Another possibility is that some children become socially withdrawn as a way of filtering out the excess noise and confusion in chaotic homes (Evans, Rhee, Forbes, Mata Allen, & Lepore, 2000
). Moreover, children in chaotic homes may be inappropriately extending this filtering to potentially beneficial social interactions and carrying it over to the classroom. If under the influence of genetic factors, a ‘tuning out’ strategy could explain the common genetic link between household chaos and school achievement. Notably, however, children's accounts of environmental confusion and disorder in the home predict school achievement even after accounting for problem behaviour and inattention in the present sample. The many potential behavioural mediators of the genetic link between chaotic homes and poor school performance are a rich area for exploration.
Finally, given that the present study measured perceptions of the environment by questionnaire, children's perceptions of the chaos in their homes could have been influenced by additional cognitive, affective and personality factors for genetic reasons. However, environments that are not measured by questionnaire are still found to be heritable (Plomin & Bergeman, 1991
Implications and future directions
This study highlights the importance of supplementing family-wide measures with individual-specific measures for the study of factors relevant to school achievement, and developmental outcomes in general. Child-specific measures within the genetically informative twin design provide a means to quantify the contribution of the child's (and their parents’) genes to their environment and its link to academic outcomes. To the extent that the link between chaotic homes and academic achievement is the result of shared experiences like unstructured television watching and irregular sleeping patterns, imposing structure will be beneficial. However, a common genetic contribution to the link between family chaos and low school performance suggests that additional targets for intervention may be found in as yet unidentified genetically driven behaviours of the child or their parents.
The present study focused on latent genetic and environmental factors linking family chaos and school achievement. However, underlying the genetic effect on experience of the chaotic home and its link to school achievement will be specific genetic variants. Isolating these variants and tracing out their effects, may tell us something about what behaviours or propensities underlie the heritable effect in children's experience of high levels of chaos in the home, and their poor performance in the classroom. If the common environmental component of the association between chaotic homes and school achievement represents a causative effect of home chaos on achievement – a possibility still to be tested – then imposing structure and order are obvious interventions. Future work to understand the shared environmental link between the experience of organization and routine at home and academic achievement will be informative about which routines and patterns are amenable to intervention. However, targeting behaviours like different children's perceptions and coping response when immersed in particular environments, may be a complementary strategy. Although the sample is representative of the UK population, the generalizability of the findings to populations in other countries, with different demographics, may be limited.
There are many potential background variables that could influence CHAOS and school achievement. These background variables are typically not twin-specific, but rather family-wide measures (e.g. socioeconomic status, SES) that could have an effect on the mean level of CHAOS and achievement, as well as a moderating effect on both measures and the link between them. Because ‘correction’ for obligatorily shared measures would have the same effect on both twins in a family, and our goal was to understand individual differences, we focused on the link between CHAOS as measured and school achievement in a genetically sensitive design; that is, on the origins of the covariation within pairs in context.
The environments we find ourselves in give opportunities to act out our genetic predispositions, to re-shape our surroundings and to select new environments and social interactions informed by our experience. We infuse the psychosocial environment of home with our particular blend of genetic preferences, and, as it turns out, some of the very same ingredients are evident in our school performance.
- Chaotic home environments, characterized by disorder, unpredictability and environmental confusion, are predictive of poor cognitive, behavioural and academic outcomes.
- But children play a role in selecting, modifying and shaping their home environment: a child's experience of family chaos is influenced by their genetic propensities.
- What this study shows is that common genes, as well as environments, link children's experience of the chaotic home and their school achievement.
- The implication of genetic effects on the chaos–achievement association is that genetically influenced behaviours (and perceptions) of the child and their parents are potential targets for intervention that will complement efforts to impose structure on the family home.