The extent to which our development is affected by nature or nurture – our genetic make-up or our environment – may differ depending on where we live, according to research funded by the Medical Research Council and the Wellcome Trust.
In a study published today in the journal Molecular Psychiatry, researchers from the Twins Early Development Study at King's College London's Institute of Psychiatry studied data from over 6,700 families relating to 45 childhood characteristics, from IQ and hyperactivity through to height and weight. They found that genetic and environmental contributions to these characteristics vary geographically in the United Kingdom, and published their results online as a series of nature-nurture maps.
Our development, health and behaviour are determined by complex interactions between our genetic make-up and the environment in which we live. For example, we may carry genes that increase our risk of developing type 2 diabetes, but if we eat a healthy diet and get sufficient exercise, we may not develop the disease. Similarly, someone may carry genes that reduce his or her risk of developing lung cancer, but heavy smoking may still lead to the disease.
The UK-based Twins Early Development Study follows over 13,000 pairs of twins, both identical and non-identical, born between 1994 and 1996. When the twins were age 12, the researchers carried out a broad survey to assess a wide range of cognitive abilities, behavioural (and other) traits, environments and academic achievement in 6,759 twin pairs. The researchers then designed an analysis that reveals the UK's genetic and environmental hotspots, something which had never been done before.
"These days we're used to the idea that it's not a question of nature or nurture; everything, including our behaviour, is a little of both," explains Dr Oliver Davis, a Sir Henry Wellcome Postdoctoral Fellow at King's College London's Institute of Psychiatry. "But when we saw the maps, the first thing that struck us was how much the balance of genes and environments can vary from region to region."
"Take a trait like classroom behaviour problems. From our maps we can tell that in most of the UK around 60% of the difference between people is explained by genes. However, in the South East genes aren't as important: they explain less than half of the variation. For classroom behaviour, London is an 'environmental hotspot'."
The maps give the researchers a global overview of how the environment interacts with our genomes, without homing in on particular genes or environments. However, the patterns have given them important clues about which environments to explore in more detail.