I’m adopted. I did one of those kits and actually ended up finding my birth mother, and it’s 100% her. her side of the family is 50% germanic and 50% english. my test results show me as german, romanian, polish, and ukrainian.
I guess what I’m asking is, how can I not have any english in my dna results? mathematically I can see it possible but it seems pretty crazy.
In: Biology
I did one also because I don’t know my biological mother or her side of the family. Her birthplace is Thailand. When the results came back it said Vietnam and China. Looked into more and basically not enough dna markers or something so those are the regions I matched? It was confusing but interesting.
Let’s start with how DNA is inherited.
Humans have 46 chromosomes, meaning 23 pairs. So for each chromosome, you have one copy from your mother and one from your father. Each chromosome contains a large amount of genes encoded in the sequence of the DNA.
Let’s focus on one chromosome to deliver the concept, let’s call it Q. So you are made when your father’s sperm fertilizes your mother’s egg, and they combine to form your first cell, a totipotent cell (capable of becoming any type of cell in the entire body). Since you have 23 pairs of chromosomes, the sperm contains 23 total chromosomes and the egg too, when they combine, you get the 46. The sperm would then contain Qf and the egg Qm. But your parents have also Qgf and Qgm (gf for grandfather, gm for grandmother, relative to you). How did they choose which one to put in the sperm or egg? Well they didn’t. They actually take these two Qgm and Qgf and recombine them randomly while keeping genes intact. So if Q contains genes A, B, and C, then they would recombine the two Q chromosomes to generate, for example, a chromosome containing Agf, Bgm, Cgf or maybe Agf, Bgm, Cgm. So the genes get shuffled. Then they deliver this recombined chromosome (along with the rest of them) in a germ cell, the sperm or egg. That’s how you inherit DNA.
Now, regarding the results of your DNA kit, well if your mother is 50/50 Germanic/English, and you also have your father in the equation (don’t know his origins), the probability then will converge on your DNA being 25/25 Germanic/English. It could be less, it could be more, it’s only approximate due to the random recombination described above. You’re EXACTLY 50% your mother and 50% your father, but you’re only approximately 25% of each grandparent.
How could the kit not detect any English DNA? Well that’s because those kits aren’t nearly as accurate as you think. Sure, the actual DNA extraction and sequencing of the loci (locations on your genome, they don’t sequence the whole thing lol), is accurate, but what is off is the analysis. Someone asked about this ages ago on here, and I posted a comment. Here is the link so you can read my explanation there: [https://www.reddit.com/r/explainlikeimfive/comments/do9ya1/eli5_how_do_the_ancestry_experts_know_where_i_am/f5l6ozv/](https://www.reddit.com/r/explainlikeimfive/comments/do9ya1/eli5_how_do_the_ancestry_experts_know_where_i_am/f5l6ozv/)
**ELI5:**
Your DNA is like a book hundreds of pages long with parts written in different languages. “Ancestry” companies pick a number, let’s say 100, words spread throughout the book and look up which language they are in. Then they make statistics about which languages came up at which percentage.
As you may know, there are words that are the same in several languages (e.g. “will die” means something totally different in English and German, but it’s written the same), this also happens with DNA, so unless you picked some pretty unique words you won’t be able to figure it out.
**tl;dr:**
The companies only check a small sample of the DNA, the rest is disregarded. This small sample might be biased.
There was a notorious case a little while ago where a set of identical triplets sent their DNA data to 3 different companies, and while their DNA was the same, they each got slightly different results in terms of where their ancestry is from. Like one might be 50% Germanic, 2% French, 8% Irish, etc., and another might be 42% german, 9% French, 24% Irish, etc. ( [https://www.today.com/health/are-home-dna-kits-accurate-identical-triplets-try-3-them-t119472](https://www.today.com/health/are-home-dna-kits-accurate-identical-triplets-try-3-them-t119472) )
These percentages can’t be trusted, there are too many variables. But bigger picture, they do have validity. Like there was a woman who was 100% Irish and her results came back 50% Irish, 50% Ashkenazi Jewish. She thought they were full of crap and the test was worthless, but then did *years* of research and found that her father was switched at birth in the hospital in 1913 by accident, and a kid from a Jewish family was raised in an Irish family and vice versa. And all of the genealogy tests done by her family and the other family in an effort to unravel this mystery told the same story in terms of the general outline–it correctly identified relationships and ancestry even when the people themselves had bad information. ( [https://www.irishcentral.com/roots/genealogy/alice-collins-plebuch-dna-test](https://www.irishcentral.com/roots/genealogy/alice-collins-plebuch-dna-test) )
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