This study aims to see 400 twins, both female and male, by spring 2005. We hope that for the first time we will be able to elucidate the genetic basis of pain reporting. We are conducting experiments which examine pain thresholds in models of acute and chronic pain to identify the heritable basis of a range of pain modalities. They will provide an insight into the genetic and environmental basis of pain reporting in humans. The results will provide a rational basis for both assessing the importance and clinical relevance of future studies of the genetics of pain particularly in relation to rheumatic diseases.