How do forensic scientists use DNA?

Every human has unique DNA (except for identical twins who share the same DNA, as they both came from the same initial cell). Forensic scientists use the unique nature of DNA to help catch criminals.

They collect human cells left at a crime scene, perhaps from blood, saliva or hair. The forensic scientists then extract DNA from the cells, analyse it and make a DNA profile.

The DNA profile is then checked against a database of other profiles. If there is a match, it could be used as evidence.

Genetic profiling can be controversial. The table below summarises some of the advantages and disadvantages of using this technique.

AdvantagesDisadvantages
DNA evidence is reliable as it is highly unlikely that two people would share the same profile, except in the case of identical twinsStored DNA data might get into the hands of insurance, loan companies or employers who could analyse your DNA for predisposition to disease and refuse your business because of it
DNA profiles can be used to determine paternityStorage of DNA profiles can be seen as an invasion of privacy
DNA profiles can be used to identify genetic disorders earlyTheft of DNA profiles from a database is a real threat
DNA profiles can be used to place suspects at a crime sceneIt is possible to plant DNA at a crime scene giving false evidence, or an innocent person’s DNA might be at the scene even though they had nothing to do with the crime