DNA profiling (or genetic fingerprinting) has proved to be a revolutionary tool for forensic investigators as a means to identify potential suspects, exonerate the innocent and convict the guilty. But, like any forensic technique, it has its limitations. One limitation is in cases involving identical twins, something that has raised technical, legal and ethical problems — until now.
The more closely related one human is to another, the more similar their DNA profiles. For example, the probability of a DNA match between two random, unrelated individuals is in the region of one in a billion. For two full siblings, the probability drops to one in 10,000. Identical twins present the same DNA profile.
In forensic investigations, this presents problems. Under the ethical premise that it is better to let ten guilty men go free than to imprison one innocent man, if the courts cannot decide which twin is responsible then both must go free. There have in fact been a small number of high-profile cases where the suspects were identical twins, leading forensic genetics researchers to explore how this could be addressed. Now we’ve come up with a solution, recently published in the journal Analytical Biochemistry.