Differences in non-pathological cognitive ageing provide a useful case study for the opportunities and challenges facing cognitive science as it embraces advances in genetics. One replicated contributor to these differences is variability in the gene for apolipoprotein E. Genetic variations that influence neurodegenerative diseases, learning and memory, cardiovascular disease, and oxidative stress are among the candidates for influence on cognitive ageing differences. The area suffers the same problems as other domains in which quantitative trait loci are sought: uncertainty regarding the genetic architecture, unreliable strategies for candidate gene selection, lack of power leading to unreplicated findings, and poor characterisation of the phenotype. However, current progress in genetic knowledge, technology and informatics will contribute to progress in this important area.