Genetic studies of pathological gambling: a review of methodology and analyses of data from the Vietnam Era Twin Registry.

Twin studies represent an important and powerful approach to estimating the relative contributions of environmental and genetic factors to the expression of psychiatric illnesses. In this article, we first explain the rationale for using large populations of monozygotic and dizygotic twin pairs to estimate genetic and environmental contributions to a disorder and the statistical modeling associated with this approach. We then review results from studies of the Vietnam Era Twin Registry that use this methodology to examine the etiology of pathological gambling (PG) behaviors. The results provide strong evidence for genetic contributions to the development of PG in men and set the foundation for future studies aimed at identifying the manner in which specific genes and environmental factors individually and in conjunction contribute to PG.