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
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/)
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