Photograph of a teacher and students in a 1970s classroom

In your genes

How much of ‘me’ is determined by my genome?

Our personalities and behaviours are undoubtedly influenced by our genomes, but there are real difficulties in researching the links. A lot of the personality traits you might potentially want to study – such as optimism or aggression – can be hard to define. And, as with complex physical traits, genomic analysis typically finds many DNA variations that only have weak associations with the behaviours in question.

Geneticists who work in the area seem to have a persistently optimistic trait, though, and are continuing to work on the origins of a whole range of behaviours, including abilities such as reading and maths. They continue to find new clues to the connections between genetics and life histories.

For example, there is evidence from psychological studies that children’s school performance is influenced by how smart they think they are – their ‘self-perceived ability’ (SPA). In 2009, Robert Plomin and colleagues at King’s College London, who work with a large database of twins, reported that SPA is highly heritable. So while there is still a self-fulfilling prophecy involved, it may be at least partly due to some genetic influence on self-belief, rather than solely the messages children get from teachers or parents about their ability.

Edinburgh University researchers recently studied 800 sets of twins to try to work out whether genes or environmental influences had a greater influence on personality. They found that identical twins (who share all of their genes) were more likely to have the same personality traits as each other than non-identical twins (who share about half of their genes).

But there are some personality traits that do not seem to be governed by genetics. A 2014 study in more than 1,000 twins and relatives, for example, found that trust is a trait that’s shaped solely by the experiences we have during our lives. Researchers found this was the case when they looked at how much people trusted others, as well as how much they thought others trusted them.

Lead image:

Phillips Academy Archive and Special Collections/Flickr CC BY NC ND


About this resource

This resource was first published in ‘Genes, Genomes and Health’ in January 2010 and reviewed and updated in December 2014.

Psychology, Genetics and genomics
Genes, Genomes and Health
Education levels:
16–19, Continuing professional development