Gene dilution over generations: does Elizabeth II have any of The Conqueror's Genes?

From The Selfish Gene by the Dawkster:

Is that true? How could those billions of ‘genes’ down to the last have disappeared over just 1000 years? Does that mean she really isn’t related to him anymore than I am? (I have no Conqueror genes myself probably).

(So my pedigree IS better than I thought).

Is Dawkins right? Then really there’s no point in passing down genes? (Oops that might be too debatey)

Keep in mind that ERII is almost certainly descended from WtC through more than one line, so he’s not just a one-off ancestor from 1,000 years ago.

But ignoring that for a moment, and assuming 1 generation = 25 years, we have 40 generations between WtC and ERII, or 39 generations between her WtC descended parent and WtC himself. That parent has, maybe, 1/(2^39) of WtC’s genes. Since ERII gets only half her genes from that parent, it’s quite likely none of WtC’s genes will get through the gate. Or, rather, think of how many times a tiny fraction of genes have to get through such a 50/50 gate in the many generation between WtC and REII. Odds are very high that one gate will shut them all out.

Now, keep in mind that most of WtC’s genes were the same as everyone else’s in the general population, so although REII might not get the actual genes from WtC, she would have identical genes from other ancestors. Which is a bit of a different thing, but is still relevant to the discussion, I think.

Wouldn’t the genes of the X (in maternal line) and Y (in paternal line) chromosomes exceptions?

Given that ERII is female and WtC was male, that may be true. But if you counted back 30 generations or more in a direct female line, you’d find the mitochondrial line easily detectable.

Not the X, because that can go through both males and females and recombine along the way.

She almost certainly has some of WtC’s genes. For example his Cytochrome C gene.

She probably doesn’t have any gene that was unique to WtC, though.

Just to run the numbers: Taking 40 generations between Bill and Liz, and assuming that a gene is passed on to the next generation with 1/2 probability, the probability of Liz inheriting one of Bill’s genes is about one in 1.1 trillion. For comparison, the number of genes in the human genome is only about 23,000 (discounting “junk DNA”.) This works out to about a one-in-50 million chance of inheriting one or more genes over 40 generations — pretty long odds.

If you go back that many generations, it’s not so likely that every single ancestor in one’s family tree is unique.

Except that assuming one line of descent is clearly way, way, way, off. That would imply ERII had 2^39 unique ancestors living at the time of WtC; and I don’t think there were (about) a trillion humans around at that point.

Now, we don’t know for sure the exact line of descent so all we can do is estimate probabilities. After all it’s quite possible that all of WtC’s descendents died out at some point, and it’s also possible that due to a freak of descent and recombination WtC inherited all (OK, all non-Y-chromosome-unique) of her genes from WtC.

But for an average, a reasonable way to get a quick estimate is to decide how many people living around 1066 could reasonably be an ancestor of ERII. [Corrections in math/estimates welcome from here on out] Looks like England had population of about a million in 1000; let’s add 9 times that for the rest of Europe (and occasional outsider), then cut that total in half to get it down to those of breeding age, giving us 5 million or so reasonable potential ancestors. I’ll assume WtC is going to have a greater chance of being ERII’s ancestor than your average peasant, let’s wildly guess at a 100 times greater chance (on retrospect probably low, but I’ll go with it). So that means WtC forms about 1/50,000th of ERII’s ancestry [Which implies that WtC is ERII’s great^37 grandfather in about 200 million different ways. Because she has potentially about a half trillion]

Quick search shows about 25,000 human genes, so, surprisingly if my math is correct, it’s about a 50/50 chance ERII inherited a gene from WtC directly. [This assumes no mutations, no sex-related genes or chromosomes, and no selection for genes along the way. All clearly wrong assumptions, of course]

For a limiting case of “not so likely” – if all your ancestors were unique, at 40 generations, you would have 1 099 511 627 776 ancestors, which is more people than existed.

FWIW, Pedigree Collapse takes care of this.

Given pedigree collapse, it’s probably the case that a significant percentage of people with British ancestry are descended from him somewhere in their family tree, especially people who have known royal or noble ancestors. Because so many of the royal families of Europe are related anyway, people with any royal or noble ancestry anywhere in Europe probably stand a better chance at being descendants of WtC than they do winning the lottery.

Anyone have a cite regarding the number of estimated descendants of WtC?

I recall reading that the population 1000 years ago can be neatly divided into two categories:

[ol]
[li](about 20%) people who left no descendants today.[/li][li](about 80%) people who are ancestors of all people living today.[/li][/ol]

With very, very few people in the category of “people who are ancestors of some, but not all, people living today”. WtC is likely to be in the latter category, at least for the British, meaning “better chance than winning the lottery” is an understatement.

I am assuming that REII has no Y chromosome, but I guess you never know…

The X, as has already been pointed out, can be had from the father as well as the mother, and Y is only preserved along the male-ancestry-only line. You would only get WtC’s Y if you were a direct, male line descendant. Chances are, no one like that is alive today.

Cite? :slight_smile:

I don’t know, him being a king and all, I’d expect that there would be quite a few. By comparison, a hefty chunk of the population of Asia has Genghis Khan’s Y chromosome.

GK had a harem of thousands of women. His sons also had enormous harems. How big was WtC’s “harem”, and how big were his (4) sons’ “harems”?

And, btw, we don’t know for certain that the aforementioned Y chromosome actually came from GK.

This thread appears to take the position of WtC as the starting point of a family tree and passing his genes downstream.

But just to complicate things; wouldn’t WtC have shared gene patterns with a lot of people alive in his time that had been passed down from their shared predecessors? (For that matter, did he have any siblings?) So, could E2 in theory have acquired similar gene patterns by multiple paths rather than just in a direct path from WtC? Is this perhaps related to pedigree collapse?

And as a side note, didn’t The Master address Pedigree Collapse in one of his articles?

He did, and I’m annoyed that I forgot about the phenomenon when I made my earlier post. Mea culpa.

Read the first reply to the OP.