Did it once. Having a written family history to compare their results to showed that my parents had three more children than the one sibling I grew up with, all younger than I. Now how can that be? maybe an "invisible" family. That would fit the JW teachings of Christ's presence I guess.
Never did, and never will do the DNA thing. But my best friends Scandinavian bred father did and it came back that he was 80% Asian and 20% black African. One of the most round eyed, pale skinned, blue-eyed, blonde haired Asian Negros I have ever seen.