Probabilities of Incorrect Decisions in Paternity Cases Using Multilocus Deoxyribonucleic Acid Probes

SUMMARY Deoxyribonucleic acid (DNA) profiling is now commonly used in attempts to resolve disputes concerning paternity. In this paper, we evaluate simple rules based on the DNA profiles of the mother, child and putative father that could be used to decide whether the putative father is or is not the father of the child. Probabilities of deciding that the putative father is the father when he is not and of deciding that he is not the father when he is are calculated. We also discuss the use of more complicated rules taking into account bands other than those present in the child but not in the mother, the effects of inbreeding in the putative father and of relatedness of mother and putative father, and the importance of conditioning the probabilities of wrong decisions on the number of bands in the putative father's profile.