Over twenty years ago, Kathleen Jordan and Michael Lynch analysed the Polymerase Chain Reaction (PCR), a technique for copying specific DNA sequences, observing that its scientific identity shifted as it was applied in medical, forensic, and public realms. According to Hopman, they concluded that PCR is adapted to various contexts rather than being a uniform tool.

Today, PCR remains prevalent in forensics, and Jordan and Lynch's insights are relevant as we explore Forensic DNA Phenotyping (FDP), which predicts physical traits of unknown suspects from crime scene DNA. This process transitions from research labs to forensic settings and investigations, each governed by different logics.

In research labs, FDP aims for individualised facial composites, focusing on accuracy and unique genetic traits. In forensic labs, constraints limit results to shared genetic traits, which Hopman terms the logic of commonality. Finally, for police investigators, FDP results guide their focus on specific groups, reflecting the valuing logic.

Hopman's analysis reveals a disconnect between research aspirations and forensic realities. While individual composites may be the goal in labs, broad phenotypic categories often prove more practical in investigations. As FDP technologies develop, particularly with biomarkers, understanding their integration into research and forensic practices becomes critical. The Dutch public prosecutor's mention in 2018 of composite sketches based on DNA reflects the tension between evolving technology and the expectations it generates, highlighting the need for further exploration of FDP in forensic contexts.

Read more in the source.

Source: Hopman, R. (2020). Opening up forensic DNA phenotyping: the logics of accuracy, commonality and valuing. New Genetics and Society. https://doi.org/10.1080/14636778.2020.1755638

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