DNA profiling of biological material has had an enormous impact on forensic science because of its potential role in associating an individual with a crime. As two examples, the biological material may be taken from the clothing or body of a victim and found to have the same profile as that of a person suspected of assaulting the victim, or it may be from a stain in a vehicle and found to have the same profile as that of a missing person thought to have been abducted by the owner of the vehicle. The key point is the explicit recognition that present genotype proportions are shaped by events that have taken place in previous generations. Related individuals carry alleles from recent common ancestors and these alleles can consequently be identical through their descent from that ancestor. For mass disasters there may be large numbers of missing people and their family members to associate with large numbers of remains.