We developed a deterministic model to optimize DNA fingerprinting effort in the presence of gene flow during the application of Breeding without Breeding. The method considers trait’s heritability, level of gene flow, selection differential, and the proportion of progeny test subjected to fingerprinting (truncation). All the model’s variables individually or in concert proved important; however, the trait’s heritability magnitude played the most important role in minimizing the selection of contaminated individuals and it could be used as a surrogate to traits with low heritability.