Is it time to stop talking about nature versus nurture? It’s probably worth keeping a very open mind on the whole subject, as research continues to inform us with fresh evidence and perspectives for both elements.
Genes and environment are deeply entwined
The latest science shows that genes and environment are deeply entwined. We know that part of who a child is comes from their genes, which contain instructions to build their body and wire their brain. We also know that the culture they grow up in can shape their brain and body in fundamental ways.
New evidence suggests that a dividing line between nature and nurture doesn’t really exist. It seems that the environment causes certain genes to turn on and off (a process called epigenetics). There are also genes that regulate how much the environment affects someone. Genes and environment are so inter-connected that it is almost unhelpful to separate them into ‘nature’ and ‘nurture’. Apparently, emotions like joy, sadness and fear, which feel inborn and automatic, are in fact a product of culture. Culture allows one generation to pass information on to the next without it having to be carried by genes.
According to Lisa Feldman Barrett PhD*, a leading scientist known for her revolutionary research in psychology and neuroscience, culture does not determine destiny and neither does genes. Genes and the world you live in combine to make you who you are, and we are therefore all partly responsible for wiring each other’s brains, and the brains of the next generation, through our words and actions. We have the kind of nature that requires nurture, and the two are interconnected.
Parents curate children’s physical and social worlds, and their brains adapt themselves to that world. As children grow up, they perpetuate that world and will eventually pass that culture on to the following generation through their own words and actions, wiring their children’s brains in turn. This cultural inheritance is an efficient, flexible partner to genetic inheritance, and means that the process of evolution doesn’t require all wiring instructions to be in genes.
The way the brain becomes tuned to the languages heard as a baby is just one example. Similarly, if children are exposed to adversity in early life, it may activate certain genes and suppress others, wiring their brain to deal with adversity that may arise in the future.
Literacy, numeracy and cognitive ability
Considering schooling, because literacy and numeracy are the target of much early education, it would be reasonable to assume that they are less heritable than general cognitive ability, which is not taught directly and is viewed as an aptitude inherent in individuals. Another reason for thinking that literacy and numeracy are less heritable than cognitive ability is that literacy and numeracy are relatively recent human inventions, whereas the abstract reasoning and problem solving central to cognitive ability appear to have been key to human evolution.
Some results on genetic research do support the assumption that school achievement in reading and mathematics is less heritable than general cognitive ability in childhood.
For example, a study of more than 2,500 representative twin pairs in the United Kingdom** found substantial heritability for literacy and numeracy in the early school years and lower heritability for cognitive ability.
Identical twins, identical outcomes?
Genes have been shown to influence how well children do at primary school, at the end of compulsory education, and even in different subjects. However, less is known about how genetic and environmental factors contribute to how well a child continues to do academically throughout their time at school.
Using twins, researchers can estimate the proportion of differences that can be explained by genetic factors. Identical twins share 100% of their genes, while non-identical twins share on average 50% of the genes that differ between people, just like other siblings. If identical twins are more alike on a particular trait than non-identical twins, such as school achievement, they can infer that it is influenced by their genes. They can then estimate the heritability of that trait.
When standardised test grades remained similar between primary and secondary school, they found that about 70% of the stability in achievement was explained by genetic factors, while 25% was accounted for by the twins’ shared environment, such as growing up in the same family and attending the same school. The remaining 5% was explained by their non-shared environment, such as different friends or different teachers.
When there was a change in educational achievement, where grades increased or dropped between primary and secondary school, they found this was largely explained by those environmental factors that were not shared by twins.
It’s reasonable to assume that this substantial influence of genes on the continuity of children’s achievement during their time at school can be explained by intelligence. But they found the influence of genes remained substantial – at 60% – even after accounting for intelligence, which was measured using several verbal and nonverbal tests taken by the twins over the course of childhood and adolescence.
Recent scientific advances are revealing more about the influence of genes on the individual. There has been considerable recent success in identifying genetic variants associated with educational attainment through what are called genome-wide association studies (GWAS), pinpointing genetic markers associated with certain traits. However, each genetic marker explains a very small proportion (less than 0.1%) of the individual differences in school performance.
Another method was recently developed that sums up thousands of the genetic markers found in the GWAS studies to instead calculate a genome-wide ‘polygenic score’. This score is now being used, with increasing levels of accuracy, to predict variance in a trait – such as school achievement – for people who are unrelated to each other.
As part of their new study, they used data from previous GWAS analyses to create a polygenic score for education attainment, calculating a score for one of each pair of their 6,000 sets of twins (so that everybody in this part of the study was unrelated). Their findings confirmed the results from the first part of their twins analysis – that the same genetic variants play a role in explaining why children differ in achievement at every stage in development.
Personalised learning and support
In the future, polygenic score prediction, together with the prediction of environmental risks – such as exposure to certain neighbourhoods, family, and school characteristics – might provide a tool to identify children with educational problems very early in life. This would allow early intervention and they could then be provided with individualised learning programmes.
Genetics will become increasingly useful in personalised learning as specific genes responsible for the high heritability of literacy and numeracy are identified. Even though many genes of very small effect are likely to be involved, identification of polygenic composites will make it possible to predict strengths and weaknesses and to create learning programs tailored to the individual child in the future**. The child’s environment provides additional information that can shape the approach and identify likely areas of need.
The nature versus nurture therefore debate continues to stimulate discussion whilst research uncovers exciting and influential new facts to consider as we develop future schooling and parenting for our children.
*Lisa Feldman Barrett, PhD is among the top one per cent most-cited scientists in the world for her revolutionary research in psychology and neuroscience. She is a University Distinguished Professor at Northeastern University with appointments at the Massachusetts General Hospital and Harvard Medical School. Dr Barrett was awarded a Guggenheim fellowship in neuroscience in 2019, and she is a member of the American Academy of Arts and Sciences and the Royal Society of Canada
** Literacy and Numeracy Are More Heritable Than Intelligence in Primary School
Association for Psychological Science, Volume 24, Issue 10 (Sage Journals),
Kovas, Voronin, Plomin. Published September 2013.
