Gray has drawn upon genetic evidence to argue for the existence of rodent emotionality, a model of human neuroticism. With the advent of molecular mapping techniques it has become possible to test this hypothesis. Here I review the progress that has been made, largely in animal genetic studies, demonstrating that a common set of genes act pleiotropically on measures of emotionality. More recently, evidence has emerged supporting the view that the same genes influence variation in both rodent and human phenotypes.