What is DNA phenotyping, and what has it been allowed to reveal in Switzerland since 2023?
Reading externally visible traits of the person who left a trace from the DNA. Since 1 August 2023, Swiss authorities may, under certain conditions, determine eye, hair and skin colour, biogeographic origin and age, not just sex.
Before the revision of the DNA Profile Act (DNA-Profil-Gesetz), a DNA analysis produced only a DNA profile for matching, plus the person's sex. A profile can identify someone only if their DNA is already on file or a suspect is tested.
Phenotyping reads the coding sections of DNA (those that determine traits) and estimates, with a certain probability:
- eye colour, hair colour and skin colour,
- biogeographic origin (the region the person's ancestors probably came from),
- age.
This turns a trace into a rough description of an unknown person that can be used for searches. The change was pushed by the Emmen case (2015), the rape of a young woman in Emmen (Lucerne) that left her paralysed; the perpetrator's DNA was found but matched nobody in the database. The ethical cost is that the result is a probability, not an identification (see the minority-problem card).
Go deeper:
Federal Council: revised DNA Profile Act in force (16.06.2023) — phenotyping, searches for relatives and new deletion rules from 1 August 2023 (German).- SRF: Emmen rape case, the offender's DNA is phenotyped — the case that pushed the revision (German).
Wikipedia: DNA phenotyping — what can and cannot be predicted from DNA.