Imagine a world where a near-perfect likeness could be created from trace DNA evidence collected from a crime scene. This phantom image could be printed, distributed, and used to identify a suspect.

Should forensic sketch artists put away their charcoal pencils? Not quite yet. This scenario is still the provenance of science fiction, a distant but desirable goal. In truth, Forensic DNA Phenotyping—predicting a person’s appearance by analyzing crime scene samples with suitable DNA markers—is a nascent science. But the potential exists. The scientific work just needs to be done.

Take what we can know. Eye color, for example. Because eye color relies on a combination of about two handfuls of genes, we can predict it with a few DNA markers with great accuracy, up to 90% or better.We have already found the genes, identified the predictive genetic markers, developed prediction models, designed a DNA test (the IrisPlex System), and validated it for forensic needs. A DNA test to predict hair color is currently in development.

Current use of DNA in forensics relies on database-driven comparatives. When DNA is recovered at a crime scene, a DNA profile is generated and compared to the pool of DNA profiles stored in the criminal DNA database or to particular case suspects to search for a match. When a match is not found, this approach proves fruitless and can result in abandoned cases. In such cases, Forensic DNA Phenotyping would act as another tool—a powerful tool— for investigators. Because Forensic DNA Phenotyping extracts externally visible characteristics of the sample donor directly from the crime scene sample, it can help find unknown suspects via concentrated police investigation.

In recent years, the controversy surrounding Forensic DNA Phenotyping has resurfaced, matching the pace of technological advances almost step for step. To me, DNA Phenotyping isn’t as controversial as one might think.

First, Forensic DNA Phenotyping, at least how it is envisioned right now, only relies on externally visible characteristics, the part of ourselves we carry in front of us and present to the world around us. Hence, appearance traits cannot be regarded as something private.