DNA phenotyping is the process of predicting an organism’s phenotype using only genetic information collected from genotyping or DNA sequencing.

Genetic researchers have recently begun to develop a type of DNA-typing that can identify criminal suspects based on traits such as skin, hair, and eye color, geographical ancestry, gait, and predisposition to smoking. Such visual and behavioral characteristics are part of an individual’s phenotype, the expression of his or her genes. Thus, we refer to this technology as  forensic DNA phenotyping (FDP), although it is also known as phenotypic profiling, molecular photofitting, visual trait prediction, or ethnic inference.

Traditional DNA-typing does not reveal personal information.  Instead, it determines whether two samples (one from the crime scene—the unknown or evidence sample—and the other from the suspect—called the reference sample) are from the same person.  If the samples match, police assume that the suspect is the perpetrator.  But this technology is of little use if police don’t have a suspect.