This study examined the heights of allelic, stutter, and composite peaks, demonstrating that peak heights are reliably predicted as the sum of their individual components.
It is routinely assumed when interpreting forensic DNA profiles that peaks of the same molecular size, whether allelic or stutter in origin, ‘stack’; i.e., the height of a composite peak is approximately equal to the sum of its parts. There is strong theoretical reason to believe that this assumption should hold across the range of peak heights where fluorescent response is linear with respect to template; however, recent publications have called for empirical proof of, or directly questioned, this assumption. The current study supports the long-held belief that peak heights ‘stack’ in an additive fashion. (publisher abstract modified)