A psychological bias in DNA testing

I’ve got a piece in today’s Observer about how psychological biases can affect DNA testing from crime scenes.

It seems counter-intuitive, but that’s largely because we’ve come to accept the idea that DNA is a sort of individual genetic ‘serial number’ that just needs to be ‘read off’ from a biological sample – but the reality is far more complex.

Despite this, the psychological power of DNA evidence is huge and has misled several investigations that have privileged mistaken DNA results above everything else – including the case of a shadowy transsexual serial killer that led the German police astray.

The piece riffs on the work of psychologist who was the first to show that the identification of people by their fingerprints could be biased by extraneous information and he’s now found the same with certain types of DNA analysis.

More at the link below.

 

Link to Observer article on the psychology of forensic identification.