I didn't really learn anything about close family memembers from the test. However, I did learn some intersting things about my DNA heritage. We are all just a mix of ancestry from all over the world. Due to thousands of years of the slave trade by many cultures. We all have a mix of many different ancesteral DNA from all over the world. My DNA test helped me to understand where my distant relatives were from and how they migrated through the world over time.
Ugh...these things have been a constant PitA ever since I thought it would be fun to have my wife and I find out our results. Turns out she's not her father's biological child (seems to have been a donor situation), but she doesn't know and her parents are continuing not to acknowledge the discrepancies she mentioned (some ancestry that doesn't make sense, etc). So I know because I got the emails but don't feel it's my place to blow open that family drama.
I found out because suddenly she started getting hits for half-siblings left and right. The med-student donor was apparently both prolific and a popular choice. So far I know of a half-sister in Italy (who along with the donor is Jewish) and a Palestinian half-brother somewhere in our area, while my wife's family is Christian reformed.
I'm not sure what the characteristics they were using to choose donors but seems like they were all over the map demographically and in physical appearance. One of those two found out through the test and the other through a death bed confession from their father, under the heavy influence of pain medication.
Meanwhile I also recently got a hit for a half-sibling from someone that had never met their birth father and believed it was my father. It turns out we are actually first cousins and she is the daughter of my uncle I never met as he passed the year I was born. The algorithm improved and has it flagged correctly now but that was a fun few days while I checked the possible relations for various amounts of gene alignment since I was pretty sure my dad's history didn't line up with where and when my cousin was from and born.
So overall, yeah, maybe just leave the family features opt-ed out. This is worse than when I told my then future father-in-law about the free annual credit report site and he found out about my mother-in-law's secret credit cards. Technology seems to have a knack for shaking skeletons out of the branches of my family tree.
I am adopted and was contacted by my birth mother about 10 years ago. I know nothing of my birth father and decided to take a commercial test a few years ago. I have found it interesting to know a bit more about my genetic background but take it all with a grain of salt. My experience with meeting my birth mother has shown me that there are no real breakthroughs in self-discovery except that maybe I dodged a bullet by being adopted. I have been in contact with a few relatives identified through the service but haven't pursued much.
I was part of the earliest version of the National Genographic test in 2005. It was very secure - you never disclosed personal data to them. Results were by a sample number you kept when you sent your sample... and I've lost that. But I do remember the results and they were not surprising.
I am sure the tests now are more sophisticated, and they do database matching to find relatives which my test did not (and, due to the security implementation, could not) do.
I haven't and won't take the commercial tests, but have volunteered my DNA to the All Of Us research program https://allofus.nih.gov/