I understand it matches DNA from their database, and helps you meet your blood relative, but for it to be completely accurate wouldn’t every person have to use the kit for the data to be up to date?
Also, how do people have varying percentages of nationalities? Shouldn’t DNA % be a fraction of 2 because it goes like 1/2 then 1/4th, 1/8th and so on (because we have 2 sets of biological parents)
In: Biology
So they have this list of spots on DNA where it’s common for people to have different values, they call them SNPs. They then make chips with chunks of ASO that match up to the DNA for these SNPs and record what is the specific mutation on that SNP that you have. To run a DNA test, they make lots of DNA copies, chop it up into little bits and put it on the chip, the chip’s ASO sticks to the DNA chucks that match the SNP, and it can tell what the mutation is for the DNA that stuck to it.
Anyways, ancestry.com has a chip that measures ~380,000 SNPs, this would technically be capable of differentiating between 2^380000 different people (way way more than the number of people on the planet).
For health info they can look up the SNPs and see if there are studies on them (often there are, in fact ancestry picked the SNPs based on if people think they are medically relevant).
For relationship stuff, they just see how many you have in common with other people, more in common means more closely related, and roughly the percentage in common is equal to your relationship distance (for the ones that are roughly 50% common).
For telling the countries for your ancestory they they test a bunch of people who say they are 100% from county XYZ (because they can name every grandparents birthplace and they are all close and in that country). Then they find the SNPs that they have in common but people in other countries don’t have and give those SNPs a score/weight for that county. So then they look at how the scores add up for those SNPs on your DNA
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