How does does Genealogy tests works?


Those tests that people do that tell them for exemple, where they ascesters where from? How can they find ou this information?

In: 3

They’ve collected a massive amount of genetic data from people whose families have lived in the same place for a long time and/or have proof of their ancestry, and then they compare what they found to a person who doesn’t know their ancestry and wants to be tested.

As humans spread out around the world, our genes kept mutating in random ways, and those mutations can spread in a population that is reproducing with each other but they won’t show up in unrelated populations. So for example, they test a bunch of people who live in Ireland and whose greatgrandparents were also from Ireland, and they find some mutations that are common in those people but not found in people from Cambodia or Japan or Chile, because historically the people in those other areas weren’t reproducing with the people in Ireland who had that unique version of the genes. So then when they get DNA from, say, an American who doesnt know where their ancestors are from, and genetic markers pop up that are common in Irish people and uncommon elsewhere, it’s evidence that the person is part Irish. This is done with hundreds of markers from different previously tested population groups until you have a rough picture of which groups the tested person came from.

It’s important to know, though, that this isn’t exact science, because populations have been traveling and mixing together throughout history, and the genes are constantly changing over time, so there’s no person you can get data from who is “purely” from one ancestral group. That’s why sometimes they group countries together – like saying you have DNA from Northern Europe, but they can’t tell which country or a more specific area because the same markers spread throughout the whole region of Northern Europe. It can also be inaccurate for small ethnic populations that they don’t have as much genetic data on – like US native tribes had small populations by the time genetic testing existed, and many of them do not trust or welcome genetic testing, so scientists don’t always have enough data to tell which genetic markers would be accurate ones to use for those small ancestral groups.