For the letter G, Thalia [Eley, EDIT Lab director] walks us through gene-environment correlation, a topic we think will become increasingly widely explored as methods for understanding genetic influence improve.
So, what do we mean by gene-environment correlation? We are referring to the fact that the environmental influences an individual is affected by are not always independent of their own behaviour. As such, they are to some degree under genetic influence. There are three main types of gene-environment correlation that have been described in the literature.
First are passive gene-environment correlations. These refer to the fact that in biological families, the child received both their genes and their environment from their parents. So, for example, a mum with high levels of anxiety will pass on not only some of her genetic predisposition to anxiety, but will also be displaying anxious behaviours in the home which will influence the child’s environment.
Second are evocative gene-environment correlations. By this we mean that children evoke responses from those around them, which reflect their behaviour, which is itself partly under genetic influence. So, for example, an infant who is irritable, tearful and difficult to soothe will inevitably evoke different responses from its parents than one who is smiley and cheerful.
Finally, active gene-environment correlations begin a little later in development when children start choosing their environments. For example, a child who has a genetic tendency towards shyness, is more likely to observe rather than take part in activities in the school playground. As a result, their environment will be correlated with their genetic predisposition.
There is a substantial body of evidence from the twin literature that shows that almost all aspects of the social environment, from parental discord, through positive and negative aspects of parenting, to bullying and social isolation are influenced by genetic factors (Kendler & Baker). What does this mean and why does it matter? Well, for me there are two main reasons this is so interesting. The first relates to being a parent, and the second to being a scientist interested in genetic vulnerability for anxiety and depression.
“…almost all aspects of the social environment, from parental discord, through positive and negative aspects of parenting, to bullying and social isolation are influenced by genetic factors.”
Parents respond to their children’s behaviour
There is a lot of research that shows that parenting behaviours differ in families where there is a child with emotional or behavioural problems from one where the children have no such challenges. For example, we know that parents of anxious children tend to show a higher tendency to control the environment. For some, this is interpreted as indicating that parental behaviour drives and influences the child behaviour. My view is that the reverse is likely to be at least as important a direction of effect. We have shown that parents tend to control situations when their child is anxious, and that both the child anxiety and the parent control are influenced by the child’s genes (Eley et al. 2010). A recent meta-analysis of over 30 studies indicated that genetic influences from the child are a significant influence on both positive and negative aspects of parenting (Avinun & Knafo, 2014). Another specific feature of parenting in anxious children is criticism, and in a study by our colleague Jennie Hudson (@jenlhudson), parental criticism was found to be reduced when the child’s anxiety was treated (Gar & Hudson, 2009), again suggesting that the level of anxiety in the child influences parental negativity.
Genetic influences act through the environment
“…a major component of how genes influence our emotions, is through impacting on our environments.”
The finding that so many aspects of the social environment are under genetic influences is one of the most striking, consistent and important findings to come out of the twin literature. What it means, is that a major component of how genes influence our emotions, is through impacting on our environments. This was beautifully described and aptly summed up in the title of Matt Ridley’s book “Nature via Nurture”. What this means is that we can respond to and adjust the effects of genetic risk, by supporting changes in the environment children are being reared in. Of course, we’ve known for a long time that the environment is critical in child emotional development, but we now know that this is also the way that at least some genetic risks take their effect. This means it is more important than ever that we identify as early as possible children whose environments are not ideal – those experiencing bullying at school (see our Q&A on cyberbullying here), those whose parents are struggling to cope, and we invest in supporting these children and families as best we can.
For information on supporting children with anxiety or depression see: