Jewish DNA is that which has descended from Abraham, through Isaac, to Jacob and the Jewish nation. Gravity is an attraction between masses. These things exist – regardless of your machines’ proclivities.
Including the term "DNA" in that statement is an anachronism.
Cultural identification isn't a physical law like gravity, regardless of how aggressively or emphatically that may be stated. That doesn't make it unimportant or irrelevant, but it is not a biological fact, but instead a social fact.
I'm not making either of those claims. The first is an article of faith, and the second is trivially true.
I'm stating that one can't claim a particular set of DNA patterns makes someone "Jewish", because DNA is a biological phenomenon, and ethnicity/culture/religion are cultural phenomena.
DNA patterns often reflect the history of rigid social organization patterns like tribes (and indeed are essential for genetic risk management provided by organizations like Dor Yeshorim).
But nobody was tracing ancestry using DNA until the latter half of the 20th century, so claiming DNA as a basis of tribal identity seems quite anachronistic.
No that's not what I said. I said that DNA, though inherited, is irrelevant for determining cultural identity.
If I discover tomorrow that I carry YDNA haplotype J1, that doesn't make me Jewish, either culturally or ancestrally. Nobody could claim me as ancestrally Jewish based on that either.
Having a documented lineage stretching back many generations, however, would possibly do both, should I choose to embrace it.
Then substitute it with haplotype G or E1b, or include all of them. Or swap out both the haplotype and the cultural group for different ones, i.e Y Haplogroup R1b among people from Iceland.
The particular haplotype is irrelevant to the argument, which is that genes don't define cultural identity, and at best are trailing and largely low resolution indicators of historical social patterns.
Of course people have DNA in common with their ancestors as a group, hell we share a lot in common with fish. But it's because these genes are common that they enter and re-enter your family tree at multiple points.
And your mitochondrial DNA definitely doesn't descend from Abraham, a male incapable of passing on mitochondrial DNA, so there's a reason I gloss over female line descent.
Good sign of someone arguing dishonestly is that when you call out their lies, they tell you that the truth doesn’t matter.
30 generations back (a thousand years?) you have over a billion ancestors, which is way more people estimated to have lived at the time, meaning your family tree at that depth contains the same people over and over. Of course your ancestry probably isn't uniformly distributed across the globe, but without modeling it mathematically my guess is that if you go back ~3700 years to when Abraham ostensibly lived you can find multiple people that appear in the ancestry of virtually everyone from the Old World.
Anyway intuition can often be poor when dealing with large numbers so if anyone has concrete math or research to share I'd be interested in being proven wrong.
That's my point. By "common ancestor" I meant, common ancestor common to them only. That's what I find to be unlikely.
And yes, you are right about this. There is plenty of vids on YT that explain the math
If on the other hand I consulted my family’s genealogical records that had been painstakingly maintained for generations, including only those matrilineal lines that are most solid to trace, and from that listed 1,000 folks who have the same grandfather, then my claim would not be very unlikely at all.
This case is much closer to the latter than the former.