Recent large-scale genome-wide association studies have been successful in identifying some genetic variants associated with complex human traits1. We often assume these associations will hold true within the same population irrespective of age or environmental context. However, twin and family studies show that for some traits heritability increases from birth to adulthood, a finding reflected by changing effect sizes of individual genetic variants, even into later life2,3,4. Similarly, exposure to different environments can change how our genetic variants express themselves5: one major challenge will be understanding how we can engineer our environment to mitigate life-course genetic risk.
1) Plomin, R., Haworth, C. M. A., & Davis, O. S. P. (2009). Common disorders are quantitative traits. Nature Reviews Genetics, 10(12), 872–878. doi:10.1038/nrg2670
2) Davis, O. S. P., Haworth, C. M. A., & Plomin, R. (2009). Dramatic increase in heritability of cognitive development from early to middle childhood: an 8-year longitudinal study of 8,700 pairs of twins. Psychological science, 20(10), 1301–1308. doi:10.1111/j.1467-9280.2009.02433.x
3) Haworth, C. M. A., Carnell, S., Meaburn, E. L., Davis, O. S. P., Plomin, R., & Wardle, J. (2008). Increasing heritability of BMI and stronger associations with the FTO gene over childhood. Obesity, 16(12), 2663–2668. doi:10.1038/oby.2008.434
4) Power, R. A., Keers, R., Ng, M. Y., Butler, A. W., Uher, R., Cohen-Woods, S., et al. (2012). Dissecting the Genetic Heterogeneity of Depression Through Age at Onset. American Journal of Medical Genetics Part B: Neuropsychiatric Genetics, 159B(7), 859–868. doi:10.1002/ajmg.b.32093
5) 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(9), 867–874. doi:10.1038/mp.2012.68