Understanding the genetics underlying quantitative traits and identifying the causal genes and polymorphisms that are causal to these traits is hard at the best of times, but in the case of behaviour, the more modest heritabilities and repeatabilities involved make these tasks even more challenging. Understanding the genetics of behavioural traits can have large ramifications for not only welfare (to try and reduce maladaptive stress responses to the domestic environment) but also production (where certain behavioural traits are associated with either an increase or decrease in productivity). Traditionally, linkage and linkage disequilibrium based techniques have been used to identify the genetic architecture of behavioural traits in poultry. More recently, more advanced transcriptomic tools such as expression QTL mapping and even transgenic birds have increased both the potential for identifying causal genes and polymorphisms that underpin variation in these traits.