Here is some great information on Ancestry DNA processing for users. In my opinion, it looks like the process is going to take a while before it really can give you the results you are looking for. For many users, your just going to probably get false positive results until they can genetically profile everyone in the entire world. And then there are the privacy concerns. On how they use your data, what they give to authorities by law and other ways the company makes money. Make you wonder if the information your getting is accurate or is this just another way of big brother gathering information from everyone.
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