We evaluated each kit by ordering one, just like any customer would, and tracking how long it took to arrive at the lab and to get processed. Then we compared the breadth and depth of the results to see what rose to the top. The whole process was a lot of fun, in part because of the anticipation of getting the results. Most of the kits warn that testing your DNA can lead to surprising—even life-changing—results. For example, there's the story of a woman who thought she was Irish, but her DNA test revealed she was also European Jewish, Middle Eastern and Eastern European. After diligent research, she discovered that her father, who had died years earlier, had been switched at birth with another child.
Haplogroups are a different story. Your maternal line haplogroup assignment is derived from a separate piece of DNA called the mitochondria. Since mitochondria is passed on only by mothers to their children, your maternal line haplogroup assignment only tells you about your mother's side of the family. Similarly, the paternal line haplogroup assignment is derived from a different, separate piece of DNA called the Y chromosome. The Y chromosome is only passed from fathers to sons and only traces the paternal line.
The DNA tests we reviewed either require a saliva or cheek cell sample. Saliva-collecting kits include a tube that’s marked with a fill line and sample number. The tube often has a liquid-filled cap with a stabilizer that acts as a preservative to protect your DNA from degradation during transport. Cheek swab sample kits include one or two swabs for scraping the insides of your cheeks for 30 seconds to a minute to collect cheek cells and some sort of container to place the used swabs into after collection. This prevents contamination. Our testers found upsides to both types of kits but generally preferred saliva collection kits, even though they took longer.

More controversially, some of these kits profess to tell you your biological (as opposed to actual age) by measuring the length of your telomeres (in basic terms, the caps at the end of each strand of DNA that protect chromosomes, like plastic tips at the end of shoelaces). Other tests, such as 23andMe, predict higher risks of developing serious conditions, such as multiple sclerosis, Alzheimer’s and Parkinson’s, including the test for BRCA1/BRCA2 (breast and ovarian cancer) that Angelina Jolie famously underwent, going on to have a preventative double mastectomy and surgery to remove her ovaries.