As a 45yo man who recently discovered via 23andMe that my dad wasn't my biological father, let me state that the ready availability of cheap DNA testing that ha

As a 45yo man who recently discovered via 23andMe that my dad wasn't my biological father, let me state that the ready availability of cheap DNA testing that has suddenly happened over the past few years is going to have some interesting effects on our social structure. I shudder to think about its impact in countries where familial lineage is a really big deal. Just 10 years ago, it took a real effort to do this sort of thing, but now you can have your entire DNA history - and potential familial connections - within weeks. And, as with anything that relies on network effects, each additional 'node' in the graph increases it's value in proportion to the square of the number of connected users of the system: Meaning that finding lost/unknown relatives will become easier and easier. What's amusing is how the major services - 23andMe, Ancestry.com, MyHeritage.com - avoid suggesting that you are 'half' related to anyone. After discovering my history, I joined the other sites and was confused when MyHeritage discovered someone that it had a 'high confidence' was my first cousin, because we shared a relatively high 11.6% DNA. It turns out she was my half-niece. This possibility wasn't listed anywhere on their site. Have you joined 23andMe? You know that person that shares some of your DNA and is potentially your 2nd-4th cousin? They might actually be a half-relative instead, but these services are avoiding that designation for obvious commercial reasons. The problem, I think, is that this is actually a lot more common than it seems, and they are really misleading their customers. Anyways, if you have a suspicion (as I had) that you might be the 'black sheep' in your family for reasons other than the genetic lottery, it's easier than ever to confirm your suspicions, and that will definitely affect lives for real.