Authorities === police, and other government agencies.
What could they do with this information that makes it so bad? Well, they could do something like familial searching, which seeks to identify the last name of potential suspects through a DNA analysis focusing on the Y chromosome. And a "promising" match from someone who donated their genetic info, could lead to your wrongful arrest... Don't think it could happen, try it already has
Well that is unsettling. In the article you linked it sounds like Ancestry.com was responsible for working with the police. 23andMe seems to have a better track record on privacy and claims to have resisted requests from law enforcement so far. But I agree that it's not ideal that law enforcement can even make these requests. People should be able to check their genetic health and not have to worry about being wrongfully placed at a crime scene.
What could they do with this information that makes it so bad? Well, they could do something like familial searching, which seeks to identify the last name of potential suspects through a DNA analysis focusing on the Y chromosome. And a "promising" match from someone who donated their genetic info, could lead to your wrongful arrest... Don't think it could happen, try it already has
http://www.theadvocate.com/new_orleans/news/article_1b3a3f96...