Mapping the effects of nature and nurture

Dr Oliver Davis

The age-old debate about whether nature or nurture most affects us took an interesting turn last year when Dr Oliver Davis published a paper showing that the extent to which you’re defined by your genes may actually depend on where you live. We spoke to Dr Davis, recipient of a Sir Henry Wellcome Postdoctoral fellowship, about the important role of data visualisation in his research.

Davis used data from the MRC-funded Twins Early Development Study (TEDS), which follows over 10,000 pairs of twins born between 1994 and 1996. His team looked at identical and non-identical twins and used their postcode data to investigate whether location affected the influence of nature or nurture on psychological traits ranging from IQ to narcissism, as well as physical characteristics such as height and weight.

“Among all the traits we looked at, one pattern that really stood out was the difference between London and the rest of the country” he says. “For example, while in the rest of the UK genetic differences between people were more important in explaining variation in classroom behaviour problems, London was an ‘environmental hotspot’ for this trait, with variation being largely explained by environmental differences”.

In order to make sense of the mass of data they generated, Davis plotted the information onto a map of the country. This helped the team to identify patterns in the data more easily. You can get a glimpse of the maps in this short video and the spACE visualisation software Davis developed is available to download.

These maps give us clues about how different environments may interact with genes in different ways he says. “One of the most important reasons for visualising data is that it allows people from many different fields to understand the findings and help interpret them”. That’s one focus of Davis’s new lab at UCL Genetics Institute: drawing on his unusual background in genetics, statistics and psychology to develop visual analysis tools that help collaborative teams think about the vast quantities of genetic and environmental data.

Scientists, clinicians, teachers and geographers all brought the skills from their fields to interpreting the patterns on the maps. One suggestion was that variations in inequality might be behind some of the patterns. “When we mapped income inequality geographically, we found that it did correlate well with the differences in nature/nurture influences on classroom behaviour problems” says Davis, though he is quick to point out that correlation is not the same as causation, and further research will need to follow up the association. Other factors that could drive geographical patterns of nature and nurture include physical environments such as the weather, air pollution, or water hardness, as well as social patterns such as variation between local education authorities or NHS trusts. Visualising the data in map form meant that people could suggest explanations for the patterns that the team wouldn’t have thought of themselves comments Davis. “This has helped us to target interesting environments for future research.”

Classroom behaviour problems and income inequality. Left: the environmental contribution to classroom behaviour problems, showing that London is an ‘environmental hotspot’. Right: income inequality by region, showing that London is also has the greatest income inequality.

The team are currently trying to incorporate knowledge about the DNA of the twins to see if the maps can help to identify important genes. “The Wellcome Trust have helped us to collect data on more than a million genetic variations from each person, and knowing about the geographical patterns of heritability might allow us to better find the DNA variation underlying certain traits” says Davis.

The data used for the maps were collected when the TEDS twins were 12 years old, but TEDS has data from throughout their lives. “We have 18 years of data so it will be really interesting to see if these patterns change over time” says Davis. “We know that heritability (genetic influence) of some traits increases with age, with genes contributing more to IQ and BMI as a child grows up, so it will be interesting to see if these increases occur at the same rate throughout the country.”

Mapping the data helped to bring new patterns to light for further investigation and now Davis is working with Dr Claire Haworth at Warwick to investigate how happiness, life satisfaction and other well-being measures could be included as new measures for these maps. With Dr Angelica Ronald at Birkbeck, Davis has been looking into the genetic and environmental influences on traits related to psychiatric disorders. Since the article was published last summer, the group has also been working with researchers from around the world to apply the approach to international datasets. For example, they are working with scientists at the Karolinska Institute in Sweden to look at geographical patterns for asthma.

Davis is also interested in the impact of social networks and has begun studying how the social environment may influence genomes. “This is a really interesting time to be studying the TEDS twins because they are entering early adulthood and leaving home so social support is likely to be very important”, he says.

Data visualisation is an important trend in the media, but it’s also increasingly important for research, says Davis: “The more we know about human genetics, the more complex it appears. Visualisation will help us to unravel the huge datasets, and it will bring together the interdisciplinary teams we’ll need for the next generation of research into the origins of health and disease.”

Reference

Davis, O.S.P, Haworth, C.M.A., Lewis, C.M., & Plomin, R. (2012). Visual analysis of geocoded twin data puts nature and nurture on the map. Molecular Psychiatry, 17, 867-874 DOI: 10.1038/mp.2012.68