Hopefully you may remember the story about my two different DNA results back in 2016. The outcomes between the two companies “disagreed” so much I could be two people in my opinion. I doubt I could get my brother to do this, I could hear him saying things like privacy concerns or it’s a dumb idea. Since I’m also not on speaking terms with my parents, I can’t get a comparison on which 50% I inherited.
Then NPR had a story about a person like me who was equally disappointed on how little Italian DNA they found, never mind her grandmother emigrating to the States from Italy. If you don’t want to read the article, the short answers:
- Recombination: each parent contributes 50% but you might get more of a particular geographic area than their makeup and/or sibling receives.
- The databases have huge gaps due to how few people are in these services so it looks like they’re compared to what DNA they’ve found of who has lives there lately. Kind of.
Maybe I’ll try again in a couple years. See if I get a different outcome.
I wanted to mention something I thought was missing from that DNA test article on NPR: tests for Y-chromosome and mitochondrial DNA (mDNA).
There’s a number of tests out there (National Geographic has had one that was very popular) that tests specifically for these two things, as they are a guaranteed directly-line test alone your male and female lines. That is, there’s no recombination at all. You always get your dad’s Y, and you always get your mom’s mDNA. These tests are how, for instance, they discovered “Y-Chromosomal Adam” and “Mitochondrial Eve” — the most recent common (gendered) ancestors of all modern humans.
There’s a number of fingerprints on each of these that can rather definitively place your ancestors in certain places at certain times, mapping their migration out of Africa and across the rest of the world.
Also, regarding the Germans and French being lumped together in these tests, as well as Italians and Greeks, this is likely because some of those national identities are very recent constructs, and because of their proximity and cultural affinities among one another leading to quite a bit of intermixing between them. While the French and Germans have fierce identities from one another today (and the French have had a strong independent identity for hundreds of years now), the idea of “Germany” really originates from the late 19th century and what exactly is “German” didn’t really settle until the 20th. There’s parts of the Netherlands, for instance, that were “German” within living memory, and some people still consider them more “German,” while others argue that they were never “German” in the first place despite how borders were drawn. Never mind that Gaul at one point comprised a much larger portion of Europe than today’s France does.