Monday, April 6, 2015

Using DNA to Convict the Correct Twin

     When dealing with identical twins, it is almost impossible to tell them apart genetically because they both developed from the same sperm and egg.  In the criminal justice system, it is particularly frustrating when dealing with identical twins because investigators can't tell which twin their suspect is using only a DNA sample.  By law, if investigators can't determine which twin committed the crime, both must go free.  Until now, there hasn't been a solution for this debacle but scientists have come up with a couple different solutions.  Some are more complicated, some are more expensive, but it may be worth it if it means putting a dangerous person behind bars for a while.
     One method scientists came up with is a mutation analysis.  This involves sequencing the entire genome of both twins and looking for specific mutations.  When a mutation is discovered in one twin and not the other, scientists can look for the mutation in the criminal DNA sample and draw conclusions from that.  Science is advancing every day and although expensive, human genomes aren't as difficult to acquire as they used to be so this method may prove useful and practical in the future.  Another cheaper method to potentially tell identical twins apart uses DNA methylation, which is the mechanism that turns various genes "on" and "off".  Twins grow more and more different as they age and the environment impacts how they change.  How the twins live their lives and how the environment has impacted them will change the methylation status of their DNA and that's something forensic scientists can test in DNA samples from crime scenes.

     There have been studies that show other methods of telling identical twins apart as well.  I think this is an area that needs to be investigated more because this is a problem in criminal investigations.  They believe that it's better to let ten guilty people go free than throwing one innocent person in jail, which can pose a problem when dangerous people are in the community.  Incriminating twins has always proven to be difficult, but with these new methods, it may be easier to tell identical twins apart with only their DNA.

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