DNA testing proves one twin committed a crime - but which one?

After DNA evidence showed one of the twin brothers committed a series of sexual assaults in France, police arrested both brothers. While officials are sure one twin carried out the attacks, standard DNA tests are unable to confirm which one it was, and the 24 year old brothers aren’t talking.

Police have been told it would cost upwards of 1m euros to conduct an ultra-sophisticated genetic test that would be able to tell one set of the twins’ DNA from the other.

One expert told the French newspaper La Provence: “For a normal analysis, we would compare 400 base pairs [of nucleotides] which make up DNA.”

In the case of identical twins, he added, “We would be looking at billions.”