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Comment by WalterBright | Hacker News Reader

1302 to today, that's 36 generations. 2 to the 36th means his descendants today have 1 / 70,000,000,000 of his genetic contribution.

I'd say they don't have legal standing.

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A direct paternal-line descendent of Dante, which Sperello Alighieri might very well be, would essentially share a copy of Dante's Y-DNA, which is about 2% of the human genome. This is comparable to something between 2nd cousin (3.13%) and 3rd cousin (1.5%).

Would you care to elaborate? You're talking about the Y of the XY chromosomes?

If Dante’s son had a son who had a son x 36, the Y chromosome would not have changed much

Assuming all those 36 sons were actually children of their legal fathers.

In general you can say that on average a child has 25% of their genes from each grandparent. But in the case of the sex chromosomes, we know that a male has 50% of their paternal grandfather's sex chromosomes and 0% of their paternal grandmother's sex chromosomes (and vice versa for a female); the Y chromosome is passed on whole or not at all (you can't get half of it from your mother).

Dante has no living paternal-line descendants. The reason for the unusual (for Italy) double last name Serego Alighieri was to preserve the Alighieri name despite there being only female descendants left at the time (in the 1500s). Source: https://it.m.wikipedia.org/wiki/Alighieri#Storia_familiare (in Italian)

Legal standing is uncorrelated to genetics.

An adopted child has 0% of the genetics of their father, and they are still legally their descendant.

They have 100% of his name. That is more important than biology to a lot of people.

I could rename myself to Presley, but it gives me no standing to Evlis' estate.

Correct. But actually being a direct descendant would, and that's what we're talking about here.

I think the word you are looking for is bloodline or pedigree.

Since DNA is inherited as discrete molecules, it's most likely he has 0% identical-by-descent. (Except if he's a direct male-line descendant.)

But I don't think genetics has anything to say about legal standing.

> Except if he's a direct male-line descendant

Would direct male descendants have more common DNA? Why is that?

Y chromosome is responsible for sexual differentiation creating males. it is only passed father to son.

It's fun to do the DNA calculations, but the article says "can be proposed by an heir of the convict", so it's probably not really about genetics.

But on the flip side, most people commenting in this thread are descended from Dante. So do we all have standing?

You're forgetting to double count for "incest".

This was flagged, but I think mistakenly by people who think you're joking or taking a dig. The point is there weren't 70,000,000,000 people alive in Italy back then (or, you know, anywhere ever), so it is very likely that Dante shows up in multiple branches of this person's ancestry.

I am not sure that is a correct definition of incest, as it more commonly refer to breeding between family members or close relatives, with the definition of close being up to the legal system in place. Just two people with a common ancestry would be a too board definition to be useful.

But it is correct that 1 / 70,000,000,000 is the wrong numbers of the genetic contribution. In order to find the correct number one would have to determine the coefficient of relationship of the average couple. It is going to a much smaller number, but at the same time far from actually incest.

That said, incest law in Italy is a bit weird. It is legal, except if it causes a scandal.

You would also have to know whether adultery took place which resulted in a child and whether any of the 'descendants' were adopted. It would be less work to disinter Dante and compare the DNA directly.

Also, in fairness to the poster, incest was in quotes.

Which also implies everyone is a descendant of Dante.

Not necessarily. If you are descended from historically insular communities (like Ashkenazi Jews, for example) or geographically distant communities (take Native Americans for a clear example) it is unlikely you have Dante as a direct ancestor.

You are right that in the infinite time limit, assuming nonzero mixing, either everybody or nobody will be Dante’s descendant.

Obviously. But everyone in Italy is fairly reasonable.

Ashkenazi Jews are an insular community but I don’t think they’re insular enough not to have Dante among their ancestors. They have Polish/Slavic mitochondrial DNA among many other lines, and the explosion of that population was still in progress in Dante’s time. It’s entirely possible there’s no trace of Dante’s actual DNA because an ancestry share that small can just disappear by chance. But if he has living descendants he has living Ashkenazi descendants.

I believe you're close to correct. According to a paper in 2013 by Graham Coop (an evolutionary biologist from UC Davis) every living person of European descent, if you trace their family trees back 1000 years, likely shares the same list of ancestors. And that list of ancestors is more or less all the people alive in Europe at the time who had descendants surviving to the present -- about 80% of the people alive at the time. Joseph Chang, a statistician from Yale, has also written a great deal on the subject.

Not the most detailed link, but illustrative:

https://www.ucdavis.edu/news/one-big-european-family-video/

I know you're saying that in jest but it's actually called pedigree collapse https://en.wikipedia.org/wiki/Pedigree_collapse

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