How Far Back Can a DNA Segment Remain Unchanged? Genetic Genealogy Explained
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- Опубликовано: 27 июл 2024
- How old are your chromosomes? How long can a chromosome remain unchanged from parent to child? How many generations can unchanged segments of chromosomes be inherited?
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This video focuses on the potential maximum age of a chromosome segment.
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CHAPTERS
0:00 Introduction
0:16 Principles for Determining Age of Chromosome Sequences
2:20 how many generations an unrecombined chromosome passes on to
3:03 Compare grandparent to a grandchild for unrecombined chromosomes
5:20 Use Phasing to find unrecombined chromosomes
8:45 Maximum Age Chromosome Sequences Can Be
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The twenty first chromosome makes sense as it is our smallest autosome. It was supposed to be classified in descending order as number twenty two...but somebody mis-measured it! Just a bit of trivia.
Cool. Thanks
I inherited chromosome 22 entirely from my 2nd great grandfather Cyrus Nathaniel Yeaman born in 1890. I also gave it to my daughter born in 2019 so that one is at least 129 years old.
I found DNA matches who share the same 5th great grandfather as me, making her my half 6th cousin. It's safe to say I still had some Gene's left over from my 5th great grandfather even after 7 generations.
That is not uncommon. What this is looking at is having the same segment passed down unchanged for multiple generations.
The oldest significant section of DNA (38cm) I have found dates back to a man born in 1670. Most I've only been able to trace back to 1720-ish though.
You are always doing a new part when I want to get an answer to that particular problem! You are awesome!
Glad to hear it!
I enjoy your informative and helpful DNA videos very much.
I have a minor suggestion that you clarify some of the information in this video.
: I would ask that you distinguish the biological age of the molecules of chromosomal DNA ( the nucleotides and sugars in the chromosome ) from the age of the unique information contained by the pattern of the DNA in the chromosome. The maximum age would be different in the biochemical molecule versus the information.
For instance the chemical DNA in the eggs of a female are the age of the given female but the information coded by the pattern of nucleotides in the chromosome can be as you discussed many ages older especially when the chromosome hasn’t recombined often.
Every time a cell divides 1/2 of DNA is renewed biochemically. The nucleotides used to make the new copy of the chromosome are both potentially scavenged and newly made.
Please discuss difference between the biochemical age of a molecule of DNA and the age of the unchanged information coded by the DNA molecules .
That is an interesting take on this. If you extend this out, after the egg and sperm combine and the new zygote starts to divide, the number of "original" nucleotides in each cell decreases. By the time the baby is born, less than .01% of the cells could contain an "original" nucleotide. I would guess that sometime before your teenage years there is close to a 0% chance that any of the original nucleotides that made up that zygote are still present in your body.
I'll have to watch this video again and your other videos on recombination!
Our oldest daughter has unrecombined paternal C-4(grandfather). Our youngest son has an unrecombined paternal C-2(grandfather). Our youngest daughter has unrecombined paternal C-6(grandmother), paternal C-8(grandmother), and both her paternal and maternal C-9 are unrecombined(grandmothers). I haven't completed C-10 thru C-20 yet. Our youngest son has both maternal(gma) and paternal(gpa) C-22 unrecombined and our youngest daughter's paternal C-22(gma) is unrecombined. I can't wait to see what the rest of the chromosomes show in regards to no recombinations. So far, it seems to happen the most on their paternal chromosomes.
This was a very interesting video. Thanks!
Yes. Paternal chromosomes recombine at about 60% of the rate that maternal chromosome's recombine. I have a couple of videos about this.
Thanks. I will look for those videos.
Amazing thanks Andy!
My pleasure!
great channel, I had to sub! Thanks for sharing this type of content with us 🙏🏼
Awesome, thank you!
Be sure to flood my wife's videos (the genealogy research related videos) with comments if you don't mind. I know you're subbing for the DNA content, but DNA research without genealogical research is really hard to do.
I have been binge watching your videos, and I'm learning a lot. I would love it if someone, perhaps yourself could do a video about segments, not small segments, but large segment size that we share with immediate family. I keep looking everywhere for that information, I just can't find much, no number examples anyway. What segment size do siblings share 🤷
I have done some videos similar to this (looking at DNA from siblings, grandparents, cousins, etc).
I share my entire maternal chr 20 with my grandmother and entire maternal chr 21 with my grandfather. With a half 1c2r, I share a 96 cM segment on 1 chr, while not an entire chromosome, it's still pretty big.
That's cool. Thanks for sharing. Am I assuming correctly that your grandparents have tested?
@@FamilyHistoryFanatics My grandfather tested. My mother also tested so I have two phased kits on GEDmatch that show my grandmother matches me 0 cM on chr 21 and my grandfather 0 cM on chr 20.
I'm not sure I'm posting my question in the correct place. I'm new to all this DNA testing business, so I'm just a little confused. I recently got my DNA test back from ancestry. I got the following result. 1277 cm shared across 40 segments. Largest segment 141 cm.
Possible DNA relationships from ancestry.
51% Grandparent
Grandchild
Half sibling
Uncle/Aunt
Niece/Nephew
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48% 1st cousin
Great-grandparent
Great-grandchild
Grandaunt/Granduncle
Grandniece/Grandnephew
Half Aunt/uncle
Half Niece/Nephew
So I looked on painter DNA, the shared DNA project (Blaine) and I'm getting different relationship results to ancestry. I can rule out all the grand and half relationships, but I am stuck on the other relationship possibilities. Can the largest cm segment give me any information regarding relationship. Do first cousins share a 141 cm segment. I keep trying to look for examples of what is a large segment, however I only get back back information on shared cms. If anyone can tell me if 141cm is medium or large, or if this segment could tell me anything about this relationship I would appreciate it very much, thanks.
The Habsburg prognatism appeared among the spanish Habsbuger ( 3 generations before Karl V) and disapeared totally among all descendants of Emperess Maria Theresia of Austria.
A friend of mine showed me the portraits of his great- great- great proceres : they are the copy one of the other :redish hair, blue eyes, moderate stature and high intellectual niveau as university professors.
The same phenotype constancy is also seen among the napoleonids over 6 or more generations. So a determined phenotypic manifestation can be maintained for 6 or more generations independently of the possible maternally inducible dominant expression.
Q. Interesting! Thanks for your great videos. I’m wondering, could this be a factor on the ancestry timeline on 23andme ? I noticed, for me, the 1-2 generation prediction of an ancestor being of one ‘ethnicity’ can’t be accurate. I would love to see a video about it. Thanks! 😃
You didn't share the size of that ethnicity percentage. I'm going to recommend a video and then await a follow-up quesiton. ruclips.net/video/9hbE4Vihf4g/видео.html
So, will this mess with cMs amounts, when trying to predict relationships? Wouldn’t this, make a match, seem more related then they really are?
Now about, how far back, each chromosome is.
Chromosome 1, or any chromosome, do you subtract it, from the year, you were born or your grandfather?
Would this be like, my 2nd great grandfather had black wavy hair. My great grandfather(his son) had black wavy hair. So did my grandfather, mother, brother and myself, we all had black wavy hair. My nephew (my brother's son) has black wavy hair. There is 141 years between my nephew and his 3rd great grandfather. Would this be a DNA segment unchanged?
Possibly. Hair color is determined by more than one gene on more than one chromosome.
I suppose it's also possible to have an un-recombined chromosome that would be not noticeable due to deletions, duplications, inversions, or translocations of a small segment of base pairs. But having an un-recombined chromosome doesn't result in much more than coding for the same proteins from previous generations. Depending on which chromosome and how many coding areas, as well as the influence of that particular chromosome's mate, even the coding might not be exactly the same, historically. All that said, I'm not sure anyone can assign any particular significance to an occurrence of un-recombined DNA. It's interesting. But not much more than that.
Agreed. This won't help you with genealogy, just give you a fun fact to share with friends at the bar.
Well... there are genes that lot of humans have inherited from their parents that are much older than you mention. Those are the Neanderthal and Denisovan genes that are always a trace snips that are no more than 4-6% As those are small snips... It is higher probability that the snips remain unchanged from generation to generation. The question is; why are people still inheriting these snips unchanged from their parents?
Because a SNP represents a mutation and a mutation is a random event. With 3 billion possibilities and only about 30 unique mutations each generation, it is highly unlikely that a new mutation will happen at the same location as an old mutation.
What happens with unrecombined and recombined with rare XYY
XYY wouldn't have a recombined because as far as I know (other than the tiny PAR regions on the ends) the Y chromosomes never go through recombination.
Twins dna same or different?
It depends on the type of twin - fraternal or identical. And typically, identical are very similar/
But if you're using DNA to verify you are an American Indian, when there are numerous different tribes... Or... If you are searching for Jewish influences, when there were 13 tribes after Joseph, and since Judah was only one of thirteenth of that whole family genetic base starting with Abraham, which quickly split between Jacob and Esau through Isaac, both of which had 12 starting tribal foundations, this can be messy. Especially, since to be a Jew in modern times is a very generic term encompassing twenty-four different base lines including two different Semitic tribes . And to be an American Indian this base line is ever more profound. Basic high school biology taught that a black cow and a brown cow could produce either a black cow, a brown cow, or two roans... Plus... I don't think high schools even teach that anymore, they've been turned into a globalist initiation system of brainwashing philosophies that declare the one percenters deserve all the GNP pie... But that's a totally different issue of failure with human beings... Totally off topic... For which I apologize...
The same thing really applies to all groups. The Y Haplogroup R-Z255 is clearly of Laighin origin. They share ancestors with, but not the same as the Venni, nor the Deisi, Dal gCais, Eoganacht, etc. Certainly there must be some way to determine what their autosomal DNA looked like.
Not really. Because the Y remains unchanged from father to son, you could have one paternal ancestor (thing of some seafarer) who has children with a woman in a far distant place. Over succeeding generations, his autosomal DNA is diluted out of existence, but the Y DNA remains along that male line.
@@FamilyHistoryFanatics Yeah... But the point being missed here is that being called an American Indian, or a Jew in the most generic term when there was twelve tribes, when actually your father may have been Reuben or Levi instead of Judah... Or... If your blood line comes down from Sioux or Apache rather than Cherokee, unless you have an older base line that theory goes off target...
So let me see.....you are more likely to have unrecombined chromosomes than winning the Lottery.
It depends.