The Aylor Lab studies how genetic variation controls complex traits, susceptibility to disease, and individual molecular biology. Most prevalent human diseases, most agriculturally important traits, and evolutionary fitness are complex traits, which means they are influenced by a combination of multiple genetic and environmental factors. A long-standing goal in the field is to identify quantitative trait loci (QTL) – genetic variants that influence complex traits. Discovering these relationships is challenging because the individual factors each have small effects, and because genetic variants often interact with the environment (GxE) or other genes (epistasis). Figuring out how these variants change the function of cells or molecules has been even more difficult. Understanding these genetic mechanisms will enable the translation of model organism research to humans and uncover new principles of genetics and genome science. We develop and apply systems genetics approaches that enable us to discover QTL and reveal their mechanisms.