Genetic Nurture: A New Approach to Understanding Genes, Environment and Education

Genes vs Environment – Which is more important to development?

Here’s a simple starter: what’s the area of this rectangle?

The answer is of course 24cm. If I asked you to show your working out, you almost certainly used one of the most well-known algorithms in the world: the area of a rectangle = the length (6cm) x the width (4cm).

Now here’s a harder question: what’s more important for calculating the area of a rectangle, the length or the width?

Let me save you some head scratching: the answer is neither. The area of a rectangle is a product of length and width. Both dimensions play an equal role in determining the shape’s area.

This truism extends from geometry to genetics. As the celebrated neuroscientist Donald Hebb once observed, asking whether nature or nurture is more important for producing a particular trait is like asking whether the length or width is more important for calculating the area of a rectangle. The answer is always that both genes and environment are equally essential.

This is not controversial. In fact, it’s such a widely shared view in behavioural genetics that it’s often referred to as the ‘Interactionist Consensus’. All of our traits – from our height to our intelligence- are the product of a complex interaction between our genes and the environment they’re situated in. Nature and nurture don’t conflict – they collaborate.

How do genes and environment interact?

The real question is how this collaboration works. How do genes and environment interact? In the rest of this blog I’ll look at cutting-edge research into one way this interaction unfolds and, more importantly, how it applies to education.

Even at first glance, it’s clear that gene-environment interactions are dizzyingly complex. Genes can cause us to change the environment around us. This new environment can then cause changes in how the genes of other people around us work, which can lead them to create further change in the environment. This cycle continues throughout our whole lives, with our genes and environment constantly reshaping each other.

What are ‘genetic nurture’ effects?

A new paper in prepublication by Wang et al (2021) explores how these complex gene-environment interactions apply to education. The researchers zoom in on a particular type of interaction called ‘genetic nurture’ effects. ‘Genetic nurture’ is when a parent’s genes affect how they nurture their child. For example, a parent might possess a clutch of genes that give them an especially conscientious but introverted personality. This might lead them to a love of reading, leading to a house full of books, leading to their child growing up in an environment where their living room is a library. Long-term, this may lead to the child developing strong early literacy skills and high achievement in school as a consequence. In a situation like this, we could say the parent’s genes caused the child to achieve well at school by shaping the nurturing environment rather than being passed on biologically – hence ‘genetic nurture’ effects.

How do we study genetic nurture effects?

Wang et al take the existence of these genetic nurture effects as their starting point, conducting a systematic review of 12 papers studying the extent of these effects on education. While most of the papers pull apart the messy nexus of genes and environment using statistical controls, some papers user more novel approaches.

For example, some researchers produced a ‘virtual parent’ to study genetic nurture effects. To understand how this method works, remember that when parents reproduce each of them only passes on 50% of their genes. 50% of a mother’s genes combine with 50% of a father’s genes to create an offspring’s genotype. But each parent holds onto 50% of their genes that aren’t passed on through reproduction.

‘Virtual parent’ designs take genetic data from parents and isolate the 50% of genes that aren’t passed on to their offspring. This untransmitted set of genes are referred to as a ‘virtual parent’ – a set of genes that are not biologically related to an offspring, but very well may have played a role in how that child was raised.

This ‘virtual parent’ genetic data is then correlated with educational outcome data for the ‘child’ of that parent. This statistical analysis can uncover whether there are genes that the ‘virtual parent’ has that are correlated with educational outcomes, for example high academic achievement. Any correlation could be interpreted as evidence of ‘genetic nurture’ – genes that are not biologically passed on to a child but which still played a role in their educational outcomes. This could suggest these genes play a role in how parents nurture their child.

What role do genetic nurture effects play in education?

From surveying these different studies into genetic nurture effects, Wang et al tentatively conclude that:

• 16% of the educational similarity between parents and their children can be explained by direct genetic inheritance ; 8% can be explained by ‘genetic nurture’
• As mothers on average spend more time with their children than fathers, we might expect stronger genetic nurture effects from mothers. However, effects look to be roughly equal between mothers and fathers.
• Genetic nurture effects seem to play a greater role in a child’s educational attainment (the highest level of education they reach) than their educational achievement (how well they perform at any of levels of education)
• About 75% of genetic nurture effects can be accounted for by genes that are also associated with low socioeconomic status

How should we interpret findings on genetic nurture and education?

Wang et al are reserved in their conclusions, which is refreshing in a field often dominated by absolutist rhetoric. Nonetheless, there’s a few key caveats that should be considered when reflecting on their findings:

• Percentages of variance linked to genetics/nurture (like the 16% and 8% above) are estimates about the population, not about individuals. That means this paper claims that 8% of the general educational similarity between parents and offspring can be explained by genetic nurture effects. The actual figure for any individual parent-child duo could be much higher or lower.
• The number of parent-offspring pairs in this study was just under 40,000. That might sound like a lot, but genetic research requires enormous samples (numbered in the hundreds of thousands) to detect the extremely small effects that individual genes have on complex traits. For example, a 2018 study at UCL into genetic influences on educational achievement used a sample of 1.1 million individuals. The actual true impact of genetic nurture on educational outcomes may not be detectable until research hits this kind of scale.
• While particular approaches to nurture may have genetic origins, they do not have genetic mechanisms. When a parent decides to read with their child, it is their brain and body that actually do the reading, not their genes. And this decision happens in the context of a society, culture and an individual’s life history. All of this all play a role in leading to that parent reading to their child. Gazing into the human genome will do little to enlighten us about these larger processes that lead to decisions that make a difference to children’s education. We still have lots of work to do to understand the complex route from a particular gene variant to a particular parenting approach to nurture and doing this will involve looking beyond genetics to other life and social sciences. This is the real work that needs doing before we can even come close to making claims that should influence pedagogy or policy.

Final Thoughts

While historians of science sometimes refer to the 20^th century as the ‘Century of the Gene’, genomics is still in its infancy as a science. There is a long road ahead and significant challenges to be surmounted before findings can be directly applied to educational policy. But it was ever thus. Few important questions can be answered as quickly as “What’s the area of this rectangle?”.