SCOTUSblog has a great recap of oral arguments this week at the Supreme Court in the case of Maryland v King (docket 12-207). At issue is whether or not the state, in this case the Maryland police, have the right to take and archive genetic data from individuals arrested on, but not yet convicted of, felony charges. The case is one of several potentially important cases related to genetics and DNA technology appearing before the Supreme Court this year, the most significant, arguably, being the Association of Molecular Pathology v Myriad genetics, which will potentially determine the fate of genetic patents (and resolve whether or not isolated DNA is a “product of nature” under the law).
According to the SCOTUSblog reporting, Justice Samuel Alito repeatedly raised the issue of DNA being “the 21st century fingerprint.” By this, Justice Alito presumably meant that DNA has great forensic ability to identify who an individual is and potentially establish their presence at the scene of a crime. This is true. Your DNA is in unique to you (though the vast majority of it is shared broadly by humanity as a whole).
But DNA is not a fingerprint. There are important fundamental differences between DNA and fingerprints that merit consideration in how they are viewed in both public and legal discourse. The biggest difference is that while your fingerprints might uniquely identify you, they do not say much, if anything, else about you. This is because your fingerprints are a downstream expression of your phenotype. Your fingerprints are not causative agents in any meaningful way. Your DNA, while being a wonderful unique identifier, is a pluripotent causative agent. Your DNA, rather than being a downstream expression of your phenotype, is a very much an upstream shaper of your phenotype. Depending on what traits you are looking at and your individual genetic material, your DNA has the potential to say very meaningful things about not only who you are but what phenotypic characters you possess or may possess in the future. For example, your DNA can give you a definitive expectation of developing or not developing Huntington’s Disease based on variation in the Htt gene on chromosome 4. Such definitive or direct relationships between genotype and phenotype represent a minority of potential traits one might be interested in, but nevertheless they exist. In general, the degree to which one’s genotype is directly and meaningfully informative of phenotype is probably vastly overestimated by the public as a whole, creating an exaggerated sense of fear around issues of genetic privacy. Nonetheless, research within genetics is continually adding to our knowledge of these relationships.
DNA is not a fingerprint. DNA is not merely a metric that can be used for identification purposes. DNA is a functional element that plays a major role in the downstream production of phenotypic variation. This is a point I would hope the Supreme Court would keep in mind in rendering its decision on this, and any future related cases.
