TEDS research focuses on how genes and environments affect our development from childhood through to adulthood. It turns out that the information in our genetic code is important for almost every aspect of how we grow up. And it's not a case of "nature or nurture": The general rule is that genes and environments are equally important. So most things are down to both nature and nurture.
In TEDS we are interested in how genetic and environmental factors lead to individual differences in complex traits, such as cognition, school achievement, home and school environment, health and wellbeing, personality, and mental health. The genetic influences upon complex traits result from an additive contribution of many genes which have miniscule effects. This means that there is no one single gene responsible for the traits which we are interested in, but that, when summed together, these small influences can be substantial in their impact.
Recent breakthroughs in technology make the present a very exciting time for research programmes like TEDS. It is now possible to calculate ‘polygenic’ scores for individuals that indicate one’s overall genetic propensity towards a trait.
Polygenic scores are based on results from genome-wide association (GWA) studies. These studies use large samples to identify which genetic variations are associated with a trait of interest. Polygenic scores can be calculated for any complex trait for which adequate GWA results are available. The hundreds of polygenic scores that currently exist in the TEDS dataset, and are being used in research, include many behavioural traits (e.g., educational attainment, depression and anxiety, schizophrenia) and anthropometric traits (e.g. body mass index and height).
As new GWA studies, based on increasingly large sample sizes, are reported, more powerful polygenic score predictors can be created.
At present, one of the one of the best polygenic scores available is for educational attainment (i.e., years of education). The most recent GWA study used a sample of 1.1 million participants! Polygenic scores based on these findings have been shown to predict around 12% of the individual differences in educational attainment, and 9% in cognitive performance (Lee et al., 2018, https://doi.org/10.1038/s41588-018-0147-3). In TEDS we have shown that this polygenic score can predict 15% of individual differences in educational achievement at age 16 (Allegrini, Selzam, Rimfeld, von Stumm, Pingault, & Plomin, 2018, http://dx.doi.org/10.1101/418210).