While this is a potential boon for forensics, there are more immediate worries about the privacy of the participants of the genetics studies that had been under way for many years. As Science magazine writes:
The discovery that a type of genetic data that is widely shared and often posted online can be traced back to individuals has prompted the U.S. National Institutes of Health and the Wellcome Trust to strip some genetic data from their publicly accessible Web sites and NIH to recommend that other institutions do the same.
The gravest worry was that an individual who had someone's genetic code could determine, based on the pooled data, whether the person participated in a disease study and whether they were in the disease group, or thereby glean private health information. NIH plans to ask institutions that have posted pooled data on their own Web sites to take these down, too.