DNA markers are routinely used to determine the correct familial relationship between persons or animals. This study involved the problem of determining correct family relations in a large group of individuals, focusing on the case where no nongenetic information was available. It is assumed that the true pedigree linking the individuals consists of many smaller sub-pedigrees with very distant relationships between the sub-pedigrees. The study defines a distance measure between two individuals in a pedigree, shows how to estimate the distance between a pair of individuals, and gives an algorithm that generates a partition of individuals into groups using the estimated distances. The effectiveness of this method is illustrated on some examples and in a simulation study. These examples and simulations suggest that for identifying very close relationships, the method is quite reliable with error being quite rare, a desirable feature of a clustering algorithm. The use of the clustering algorithm in a two-stage pedigree reconstruction procedure is discussed. Directions in which the analysis could be extended include performing a Bayesian estimation procedure in which priors are put onto the various distances so that the whole posterior distribution of distances as a measure of the relationship between two persons may be found. The estimated distances could be used in a pedigree search to restrict the pedigrees to look at. Applications include the identification of family groups among bodies found in mass graves and identification of family groups in animal populations. 9 tables, 9 figures, 7 references