The affected third-degree relatives method ("cousins method"-CM) shares key features with the affected-sibling method, but it groups first cousins in triads, with the hope of requiring fewer individuals to be typed. The aim is to provide an efficient and computationally convenient method of genome screening, capitalizing on the vast number of highly informative markers mapped in recent years. The nonparametric CM statistic measures increased marker similarity, making no assumptions concerning how the disease is inherited; this can be advantageous when dealing with complex diseases for which the mode of inheritance is difficult to determine. This article presents a brief statistical development of the CM method and describes the results of applying the method to one replicate of the simulated extended family data set.