CNET:  “Home DNA testing has gone from a curiosity to a competitive market in the past decade, with at least a dozen companies now competing with trailblazers such as Ancestry and 23andMe. But before we compare and contrast the available options, let’s take a look at exactly why you’d invest in a DNA testing service — including the upsides and the caveats. Services available –  If you’re using a home DNA testing service, you’re likely looking for one of three things:

Ancestry and family history: The first big draw of a full DNA test is that you’ll get a detailed breakdown on ancestry and ethnicity, and the migration patterns of your ancestors. Spoiler alert: Your ethnic background may be radically different than you think it is.
Relative identification: With your permission, some DNA services will let you connect with relatives you never knew you had — other folks with matching DNA who have used the service and likewise given their permission to connect to possible relations.
Health and disease info: DNA testing can also indicate which conditions for which you may have a preponderance. It’s a controversial feature, to be sure. Knowing that you have a genetic predisposition to a certain form of cancer may make you more vigilant for testing, but it may also lead to increased stress — worrying about a potential condition that may never develop, even if you’re “genetically susceptible” to it. The possibility of false positives and false negatives abound — any such information should be discussed with your doctor before you act upon it…”