You Have Fewer Ancestors Than You Think - Genetic Genealogy Explained
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- Опубликовано: 9 сен 2024
- The amount of DNA you receive from your ancestors varies. Discover why you may have less DNA from a grandparent, great-grandparent, and more than you think.
🤔 Why am I only related to 120 ancestors? 👉🏼 • Why am I only related ...
Using probability curves, Andy models out why you may have less DNA from a 6th generation grandparent while having significantly more from another.
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Incredible video - I'm sharing it with all my relatives. Best wishes!
Great simulation of autosomal relationships! I have a much better understanding of how DNA of most of our ancestors is lost over time. Bravo Zulu!
You're welcome
Good illustration. Much clearer.
Thank you for this excellent video, very informative! Some ancestors may come from endogenous groups so you will get more DNA than expected from that line which means less DNA than expected from others.
Endogamy can be very confusing for people. I don't envy those who have ancestry in endogamous populations.
Fascinating, and really useful - thank you.
That was such an excellent presentation, especially the data simulation. It should become required watching for anybody before they give their DNA, hoping to get extreme details of their ethnicity. It counters the RUclips videos of shocked people opening their DNA results on camera. It would also go a long way to explaining statistics to people who shouldn't be gambling. I will be citing this video frequently. One thing that you don't mention is the absolute futility of researching your ancestry back more than a few generations because you are eventually going to encounter a non paternal event, i.e. somebody is descended from a secret relationship and this is not recorded anywhere except in your DNA. You only have to go back 5 or 6 Generations, and you have looked at 100 relationships. You only need one man or woman in those 100 or so relationships to have had an illicit relationship producing a child and it makes a mockery of your further research.
I wouldn't say it is futile to research your ancestry further, so much as make birthright claims based on your research (i.e. "I am descended from Royalty"). On the other hand, go back far enough in time and you will be related to all living adults who had offspring, in which case your birthright claims are correct, but they also apply to everyone else so they imply no special relationship to you.
I see the point here, and it makes perfect sense to me on the extrapolation of the percentages; however, I am confused on how heritage is approximated. I firmly believe that the genealogy companies are getting the admixtures right: I'm an adoptee, found my birth parents and in less than a month traced my roots back nine generations. The heritage mixtures from 23&me, Ancestry, MyHeritage and the Eurogene tests at Gedmatch skew the curve of the percentages in the various admixtures, but, in essence, the computations are distributing the heritage approximations right on the mark! How can that be if the filtering of DNA drops off at 120 ancestors?
It depends, person to person. No real study has been done with verified ancestries being compared to what DNA results show. Mainly because most people don't have their ancestry complete out to 10 generations, a few lines, yes, but not all of them so the pool of people that could be a part of such study is small, and most likely not a very diverse group so the results would be limited as well.
Yes, I see that now. Well, they (23&me, Ancestry, Myheritage, and especially Gedmatch really nailed it...give or take some minor percentages of the regions. It's really all quite remarkable, and I'm still quite astonished by the accuracy and by the results.
Brilliant explanation Andrew 👏👏👏😊
Great video! I'm wondering why some of the simulated numbers are negative though? Is this a bug in the simulation?
It is, and I have been trying to isolate where and why it is happening. You can't inherit negative DNA. The joys of troubleshooting computer programs.
Family History Fanatics I get it. I teach comp sci :-)
@@FamilyHistoryFanatics you need to use logarithmic scale instead of linear one, when you deal with percents. Then, you need to use log-normal distribution, instead of normal one, while performing your simulation. Log distribution is assimetric and yields only positives
Great video, very informative.
wow - very interesting!
It’s weird some sides of my tree I constantly get dna matches and other sides it’s so hard to find matches. On my paternal grandfathers side it’s so difficult to find dna matches. It seems like most my dna is from my paternal grandmother and my maternal grandfather
Seem like it's the Same for me. 3 of my grandparents are dead so I'll never know how much DNA I got form them. Do have one still living. If they ever take the test and I have more then 25% of thier DNA than I could figure it out on one side.
This video explains that situation. This video explains that situation. ruclips.net/video/pJDjHg13QgI/видео.html
Good video. I have my mom's DNA, but only one of her siblings is still living. I have two of my second cousins twice removed and that's good enough for me. It's good to know I could do visual phasing though.
You,re absolutly brilliant mate thanks for sharing👍😀
Well others accuse me of being an idiot when they view this video so thanks.
My parents are cousins -- my father's father's mother and my mother's father's mother were identical twins. Not surprising that my DNA markers are predominately Irish. Additionally, because of my Quaker (Society of Friends) ancestors where one had to marry other Quakers, it was quite common for my ancestors to marry their cousins (one colonial uncle married his niece and had 12 children). I have over 22,000 I my genealogy database. What should I learn from my DNA?
You'll learn that separating your DNA matches can become very challenging with tree collapse. But, you will become an anchor point for others seeking our their lineage.
Very well done! Thank you!
Glad you liked it!
Where can I find this computer model?
drive.google.com/open?id=1yPAR1VdZLCVR7NgBY4ZblThFYSN_0pQcNImgze7YMXg
I want to know how come I have many American distant cousin matches because I am from North western Inglish UK decent only. With nothing else attall
What about skin color?
Why it remains....
I read a book about ancient DNA that seemed to state you could have more. It suggested that the egg divides into a certain amount of segments and the sperm a lower amount but it added up to 71 dna segments and he further went on to state that the queen of England would have approx 1751 of genetic ancestors in 24th gen about 1066 but statistically impossible for William of Normandy to be one of them because she would have 16,777,216 Genealogical ancestors. I get the concept no problem just wondering what you think about that statement. The book is who we are and how we got here.
You are mostly correct, in the formation of the egg and sperm, the cells go through two divisions which mix up the DNA from the parents. The sperm has a lower number of recombinations (from 10 to 32) and the egg has a higher number (from 25-60). There is no set number that it has to be, each time an egg or sperm is formed it will be different from every other time.
As I stated in the video, the Queen of England may have more than 120 genetic ancestors in the 24th generation (although I doubt it is anywhere as high as 1751). As to being statistically impossible to be related to the Duke of Normandy, I disagree. 1751/16,777,216 is 0.01% which is small, but statistically possible (not likely, but still possible). Usually, something is a statistical impossibility if the probability is so low as to be not worth mentioning. Think on the order of 10^-20 or smaller.
Family History Fanatics cool it wasn’t my opinion it was from a book on human genetics written by a geneticist. My personal opinion is it doesn’t really matter the results are same. There is a limited application to genetics to genealogy and I don’t personally care if I’m related through dna to a king. If they are in my tree there in my tree. I agree to the statistics. Like the Charlemagne thing geography, his status as a king with concubines the status of descendants, demographics makes it difficult to truly place a likely hood of receiving DNA. How did you come up with a different number of recombinations?
I didn't come up with them. Geneticists did. Right now there are about 40,000 identified hotspots for recombination. We know approximately how many recombinations happen each generation from comparison of DNA across the generations. Using those numbers, you can create a computer model to estimate the amount of DNA several generations down the road, which is what I did.
We may assume that 72 (7200 cM / 100) is an average number of recombination points per generation. If we take 46 chromosomes + 72, then we get 118. This is a rough estimate of fragments number per generation, and this is really close to 120
Yeah, but 72 recombination points per generation is at the top most end for females. Average # of recombinations per generation is around 35
We are related to all of our ancestors, just many we are not genetically related with.
And that's without considering that any 6th generation grandparent might feed into your ancestry more than once via different family lines
Great point. So much so, I made a follow-up video about that topic. Have you seen this one?
Related in Multiple Ways: Tree Collapse & Endogamy | Genetic Genealogy ruclips.net/video/Wlq_a-gdf9k/видео.html
Is the computer simulation available to view online or is this analysis available in text format (in addition to this video)?
Sadly no. Just what's in the video.
An undocumented computermodel = manipulation @@FamilyHistoryFanatics
I have several thousands of matches from the USA - all averaging around the 10 cM of DNA. Since my family and i are not American, and my ancestry is pretty much all British and irish, I have chosen to ignore all those thousands of American matches (I assume they are false matches) and just concentrate on the few hundreds of matches that I do get from Britain, Ireland, Australia, New Zealand and even some Canadian matches. Thanks for this computer model, It actually made a lot of sense.
Those American matches aren't necessarily false matches (although some percentage 20-40% are), but rather distant cousins who happen to have a stubborn piece of DNA that keeps hanging around. For most practical purposes, I would ignore them also until I understood how my other matches related to me (20cM and above). There is usually plenty of these to take a lifetime to solve.
There wasn't 3 billion in the Time that JUDAH was in ISRAEL, so we are much closer than we think
Correct. Which is the point I was making.
This video has made me realize why I'm having such trouble with certain lines of my tree! Just to clarify, there is a chance I may not of inherited ANY DNA from a Great Great Grandparent? But I will ALWAYS inherit at least some DNA from all of my Great Grand Parents? Possibly silly question - is all DNA created equal, or does some have dominance over the other? i.e do some Ancestors DNA get replicated far less in a whole cohort of cousins? With their partners being 'stronger' and replicated far more in all the cohort of cousins?
It's only 4 generations away so I'm sure it's rare to not share any of your 2nd great grandparents DNA
Is your claim for 50% from each parent STRICTLY accurate? I ask because my wife - who is half European (principally German, Polish and Baltic), and half English/Irish registers as 67% English/Irish, and 33% European. We know from records that there have been no incursions in either direction on either side of her family, but her breakdown is roughly 2/3 to 1/3 in her British Isles favour.
Is that with the recently updated ancestry results? I've seen some strange anomolies like this elsewhere, if that is the case I'd get on to ancestry and inform them that the algorithm is not working correctly. I'd also upload your data to GEDMATCH (with Eurogenes tests) and DNA.LAND and see what results you get there.
hailandplaice - Many thanks for that - the results were from Living DNA. I will try your suggestion later today.
Half of autosomal DNA from each parent is correct because you get one set of chromosome 1-22 from each parent.
Me Dna - My wife (see earlier post) has a breakdown of 67%/33% from one British and one European parent, according to Living DNA. However, when I put the raw DNA on GEDmatch Genesis, the proportions were almost exactly 50%/50%. It's well worth a try!
Me Dna - As advised by 'hailandplaice' (earlier post) I tried downloading my wife's raw DNA to GEDmatch, with surprising results. I have now had FIVE separate tests myself - each with (slightly) different estimations of my ethnicity. It appears that each company uses a different algorithm. Do try sending your raw data to GEDmatch - it's free!
Minute 2:50, how is it possible that someone would inherit 22,8% of DNA from a great grand parent and in turn only 21,9% from the grandparent descending from the former? Let alone the -0,9% that can be seen next to it. Is there something I'm not getting or is it a mistake?
That would be a bug in the programming that happens every once in a while. I have been trying to figure out where it is, but since it doesn't consistently appear, it has been giving me fits.
I have a theoretical question. Is it actually possible to say, only inherit DNA from one grandparent out of a pair? To be a little more specific; could I inherit all off the DNA that my father received from his mother and none (or at least negligible amounts) from his father? And if so, how likely is that?
Theoretically, yes. In practice, no. Blaine Bettinger's Shared cM chart which uses actual results people have reported show that grandparent/grandchildren share between 450cM and 1450cM (average around 850cM).
@@FamilyHistoryFanatics very interesting.
Why would my son be shown with only 47.3% shared DNA with me on 23andMe?
Two reasons, 1) he inherited a Y chromosome from you which is shorter than an X chromosome. 2) There are some small sections of the genome that the testing companies don't look at (highlighted in grey when you are looking at the chromosome browser).
Not sure exactly how 23andMe calculates their numbers, but these two reasons probably account for the reason you don't show as a 50% match.
@@FamilyHistoryFanatics Thank you for taking the time to respond. I had already figured that at least part of the difference is that he does not have my X so only had the shorter Y to count. I certainly am not suggesting that he got part of somebody else. I just wondered if others saw the same since it is always stated as 50/50 distribution. Another thought, did you just use 23andMe as an example or did you check and find that I have a kit on 23andMe???? Actually, I have a kit everywhere possible, I think. I've thought of returning to Utah and working just on genealogy again, including doing RUclips videos, but you have the video part covered so well there is no sense in my even trying. Thank you.
🧐🤔 is it possible to only get 48% from both? and how could that happen?
What part is confusing? The color coding or the surname table?
☺️ Updated itself it’s not at 50% above. oh wow they all freaked out😳
That’s discouraging for me!
Is 24 centomorgans considered statistical noise?
24cM is almost always a good match.
This may be related to this video. I have a female match that shares 17.1cMs autosomal and 58.7 cMs of X chromosome. What say ye about that?
This ancestor is related on your mother's side (assuming you are male). Probably in the last 5-7 generations since you have a autosomal match as well as a X match.
Is it possible to have a Native American 3rd great grandparent and not inherit DNA from them?
Yes. By the 3rd great grandparent, of which you have 32, you probably don't have DNA from between 2 and 13 of them, with most people in the 6-9 range. As an example, I have 5 kids and 3 of them share about 850 cM with their great grandfather. One shares 645 cM, and the fifth child shares 489 cM which is at the extreme low end of what would be expected. If this fifth child has 20 grandchildren, I would expect one or two of them to not share any DNA with their 3rd great grandfather because my fifth child already shares a significantly smaller than expected amount with his great grandfather.
Thank you for your insight. I had my DNA tested through 23&Me and I have a 3rd great grandmother who was Cherokee but they didn't find any genetic markers that were Native American. Likely I did not inherit any DNA from that one ancestor that was classified as Native American.
indians blood There certainly are full blooded native Americans left - many of them. I believe you’re referring to eastern US tribes, but also exist in smaller populations. The problem is (and here is where you’re correct) I don’t believe any samples from tribes most of us with early American ancestors would have DNA from. That said, the likelihood to have this DNA show up in DNA test is almost zero unless after mid 1800s. I have both NA and African ancestors, neither of which are reflected in my DNA...because from 1600s-early 1700s. However, it pops up in certain tests in gedmatch. Also it pops up in individual chromosomes in gedmatch, sometimes at 20% of individual chromosomes which I’m still trying to understand. Also, pay attention to East Asian, Siberian, Pacific Islander which is often the Native American. Add these up. My father has zero in most tests, but 3% at Gedmatch Eurogenes. He also has 1.8% Nigerian there and My Heritage. Consider 1 ancestor 300 years ago. Even if DNA evenly from all ancestors, it’s only 1/200+. Very tiny. But still an ancestor all the same. Another interesting tidbit. I have cousins with African Y DNA, but 0% to small amounts in autosomal. Make line is African but no African autosomal DNA. It’s confusing isn’t it?
Case: my African immigrant in 1600s was never a space but his wife was. Their grandson married an Indian. Their son married a white woman and each generation since. His Y DNA is in various 3rd cousins of mine and they connect at that line. Proves my ancestor was also the African.
Case 2: An immigrant from England. English right? Well sort of. His direct male decedents have African Y DNA. He had the African DNA prior to immigration.
Case 3: white female ancestor married a full Cherokee man in 1820. Male decedents have NA Y DNA but very small NA autosomal %.
Case 4: 1 in 200 ancestors from 300 years ago was Native. Fractionally that’s 1/200th. Percentage that’s 0.5% IF all DNA was received from each ancestor which is never the case.
Case 1: “Space” should read “slave”. iPhone autocorrect typo. :(
Is it true that all Europeans are directly descended from King Xerxes I of Persia? 🎭🩰🎨
First of all we have more than "thousands of ancestors". I will get my info from other channels thank you.
A million is a thousand thousand (which would qualify as "thousands").
@@FamilyHistoryFanatics 40 generations ca 1000 yrs we all have over one trillion ancestors! Taking overlapping and migration into consideration, we still have millions if not hundreds of millions of ancestors. Your "thousands" allegory doesn't hold up.
So this would be a way to explain people that their ethnicity results do NOT go any further than 1200 AD? If so, how is it possible to detect neanderthaler DNA in our DNA? Personally, I don't take the ethnicity results too serious and I found it very logical that we don't inherit all of our DNA from all of our ancestors. Means you never know where your ancestors came from except from maybe looking at your mtDNA & yDNA, but these are just tiny pieces of our DNA. I think most people believe that their results show them where their ancestors lived 2000 years ago. Many people actually don't know how to interprete these results. At the end of the day these companies compare your DNA to those who ALSO made this test. What you actually see is their interpretation of your DNA matching in some kind with other peoples DNA. That's nothing to get really excited about, at least for me. It shows you that your genetical make up looks similiar to those of the same area but it doesn't show which ethnicity your ancestors belonged to. In this video you basically explained that these companies just interprete the tiny pieces of our ~120 ancestor`s DNA who mostly lived a few hundred years ago. At least I made these conclusions after watching this video. The real excitement for me is to understand genetics better, especially in a genealogical way & this video clearly helped me a lot.
Thumbs up! Great work!
Calculating ethnicity and calculating Neanderthal DNA are different concepts and not relatable in the same way. Ethnicity is based on statistical probabilities of differences in reference populations of several thousand individuals. Neanderthal is based on specific SNPs that are known to exist in Neanderthal populations from the limited samples we have been able to sequence, and we don't find those same variants in Sub-Saharan African populations. Hence they likely originated in Neanderthal populations and were transferred to modern humans in the middle east.
Lumineux!
Hi
Thanks for your videos i do learn a lot from them
How many years is the 8th generation and 110 ancestors approximately 600 years ?!
FTDNA claims that MyOrigines Autosomal test goes back 2000 years how can they say that ?!
Depending on how you count generations, people have variously used 20, 35, 30, 35, or 40 years. So, 8 generations could be between 160 and 320 years ago.
I have not read or heard of a valid explanation on the ethnicity results time scale from any of the companies. I think it is heavily influenced by the marketing department.
Family History Fanatics
Thanks for your reply
So in general how far the Autosomal goes back since we know we are only connected to about 120 ancestors ?
Reliable matches can be made about 6 generations back. Beyond that it is mostly luck.
Who Grandparent do i get mostly DNA From?
For everyone it is different. YOu would have to test your grandparents to be able to find out.
Family History Fanatics that is hard as many of us can’t even test our parents. Can you look at your matches and make a guess.
@@FamilyHistoryFanatics That's why we don't share DNA with the First Scandinavians because of 120 Ancestors from any Given Generation?
I call bull crap if yer saying we don’t share all of our ancestery blood then how did we got the 128 grandpanters my 3 great grandma might have here 7 great grandma blood in here but I don’t have my 10 great grand mother blood i might not have my 10 great grandblood but my 3 great grandma probly did and I have my 3 great grandma blood in me so I have dna from my 3 great grandma and she had dna from here 7 great grandma so my 3 great grandma blood in me has little bit of her 7 great grandma in me probly .0000000000001 percent but with out my 10 great grandma I would not be here plz answer back thanks
How does inbreeding affect this? I've already found three cases of related relatives in my family tree and I suspect more.
This is actually called endogamy. I've only covered this on my channel once ruclips.net/video/ppjYzFVYH40/видео.html.
The best person to help you understand endogamy is Leah Larkin. Here's her blog thednageek.com/
Glad you found your answer.
So Marty McFly should have went back 10 generations?
That would have been nice. But in actuality, he should have gone back to wherever his brick walls were. Don't want to skip over the link between him and 10 generations back.
Too bad you can’t take that great grandparent “percentage” (no matter how small) to find a lost great great grandparent…..
If only it were that easy.
It's probably not no DNA but just less than .1% DNA
Much of our DNA does phase out as each generation recombines by keeping some and discarding others. That's why children of the same biological parents can share differing amount of DNA with their grandparents and great-grandparents. ruclips.net/video/k7qqOXlp3kw/видео.html
@@FamilyHistoryFanatics So does this mean that we 100 percent have 0 dna with an ancestor that’s 12 or more generations back. Or is it just that the dna is extremely small?
120 is nonsense. You need to consult with a geneticist.
Statistics and papers published by geneticists do indicate that you only have DNA from likely 120 direct ancestors when you test autosomal DNA.
@@FamilyHistoryFanatics Hogwash. Cite your source.