The first section of "The Ethicist" from the NYT Magazine involves a person who doesn't want their siblings to send DNA samples off for genealogical purposes. They'd like to know the ethics of the situation, because "My fear is that the information will be used for other, scarier purposes".
"The Ethicist" erased the "genealogical purposes" part of the question and assumed the siblings were sending away for their medical history. First rule of always being right as an expert? Turn all question you aren't sure you understand into questions you know something about. A paragraph then followed saying that direct-to-consumer genetic testing for "medical inquiry" was so useless you're better off just collecting family medical history and using that. Which is, of course, completely ridiculous if, say, your genetics come from somewhere other than the people you think they do, which genetic testing is really good at detecting.
The Ethicist then notes that there's not a whole lot you can do beyond that, other than telling the sibs to read the fine print.
There are some really interesting issues associated with genealogy, and a lot of them are ethical issues involving the balance of the rights of some to know what others would prefer was kept unknown. In the juicy cases, that's NPEs, but in the general case it could be, well, just about anything, including general categories like family legends that turn out not to be true and unsuspected ancestry that genetics uncovers. Genealogy turns up stuff like this all the time, in paper form; genetics means you can turn it up in the more distant past and where records fail.
But you're not going to actually get to address any of those issues, if you're preoccupied with medical issues instead.