Help me understand DNA testing

[skauwt]

In another thread, someone mentioned DNA testing as a reliable way of learning about one's ancestry. They provided a link to a website that advertised DNA testing. I've always been curious and have thought about having DNA testing done, but I need to have someone explain it to me like I'm 6.

Here's what the website said:

Y-DNA - Universal Male Test, starting at $119. Males can test their Y-DNA to determine the origin of their paternal line. Note that the Y-DNA test strictly checks the paternal line, with no influence from any females along that line. Females do not receive Y-DNA, and therefore females cannot be tested for the paternal line. If you are a female and would like to know about your paternal line, you would need to have a brother or a male relative from that line tested.

Keeping in mind, I'm a male, again, talk to me like I'm 6. What exactly does this mean?

i got mine done a few months ago and have just the past week got all my final results in from my ydna and mtdna test and like yourself i hadn't a clue what was what about DNA data
these past few months Ive searched umpteen sites to learn work out a basic idea of time scope the test shows

i recommend if you can that you do it in conjunction with a clan group for example i did the test with the Chisholm clan group being a Chisholm i felt it was helpful for others also your not only helping find out info about yourself your doing that bit for other clansmen around the world that may be stuck when it comes to the paper trail on a family tree

the results you`ll get depends on what test you do the mtdna told me i descended from a women born about 25000 and 30000 years ago and i know her offspring spread through Europe (Spain ,Portugal) and eventually to Ireland which in fact where i can trace my great great great grandmother on my Gran's side to so i know my mothers maternal side has a wee story to how she got here in Scotland granted i`ll never know the 100s of generations but i get a sense of how people move over time

my male side links me with Britain/NW Europe
my male side had during the ice age lived in whats now the north sea,Denmark and south of Britain France and so on as the ice moved north the people went north too all the ice melt over time flooded land called doggerland which is now the north sea
splitting the UK and Ireland from mainland Europe granted these displaced people eventually split in Celts /beaker people and so on

after time these folk started showing different DNA groups folk have moved back and forth in time but the DNA test will show you for example if your ancestors are from the viking regions or perhaps like mine mightve been in the UK region for a lot longer than the viking era there are even a few chisholms that descend from men trapped here with the sinking of spanish armada boats so it goes to show the results could be anything

you might not be getting what you expected in all truth from the results but its the tracing of story of how your ancestors moved about and how you got to where you are
that for me was the whole point of the dna test it doesnt matter if your connected to a royal or a nobelmen at the end of the day where all people from the same folk

[mudd]

i got mine done a few months ago and have just the past week got all my final results in from my ydna and mtdna test and ...

I find this very interesting information. (From someone who can find only a limited hereditary paper trail.)

If you don't mind saying, where did you have this done?

[Alan H]

mtDNA is different from X and Y chromosome DNA.

mtDNA is DNA from the mitochondria. It tracks the maternal line. Mitochondria are little organelle's within cells which have a lot to do with providing energy for the cells functions. The theory goes that way back in the mists of time, one bacteria ate another bacteria but didn't digest it. The "eaten" bacteria discovered that living inside another bacteria had advantages. The "eater" bacteria discovered that having this particular other bacterium inside itself also conferred some advantages. Thus, the advent of the mitochondrion.

Whatever the case, mitochondria have their own DNA, which has nucleotide codes for molecular processes that occur inside the mitochondria. Many of those processes have to do with dealing with an important biological molecule called ATP. ATP is the "powerhouse molecule" of the cell. It's the molecule that cells use to power the work that they do. Sperm SWIM, don't they? That's a lot of work, isn't it? Sperm have a LOT of mitochondria. However, the sperms mitochondria are not added to a fertilized oocyte. That oocyte only contains maternal mtDNA.

You see, during the process of fertilization, the sperm attaches to the oocyte (the egg) cell membrane and injects chromosomal DNA. However, it ONLY injects chromosomal DNA, no mitochondria are injected. Therefore, the mtDNA is passed on from generation through generation through the mother, essentially unchanged except for the random and exceedingly rare process of mutation.

Different human population groups contain mitochondria which are somewhat distinct from each other, in terms of the various forms of the genes inside them. These "various forms" are call polymorphisms and are represented by subtle variations in the order of four molecules that Forrester Modern talked about: Adenosine, Thymidine, Cytosine and Guainidine.. Thus, an/some ancestral group(s) of people might be identified, by working backwards from current arrays of mtDNA polymorphisms. There are computer programs and fancy algorithms which use the principle of maximizing parsimony (parsimony = the simplest answer is the most likely answer) which can make an educated guess at what these ancestral polymorphisms would be like, by choosing the simplest possible series of mutational events that might result in the modern array of polymorphisms.

In fact, since there are estimates of the average rate of mtDNA mutation, some researchers even try to pinpoint general times when different polymorphisms occurred, thus putting some sort of timeline on the human mtDNA family tree.

To simplify...If Panache and Alan H share 12 polymorphisms in their mtDNA....and Panache and McMurdo share 8 polymorphisms, then Panache and Alan H are more closely related than Panache and McMurdo.

[Alan H]

An interesting sidelight to all of this may be found in this tale...

The Borders have long been a place where races mixed. Anglo Saxons, Celts, Danes, Romans....and...

people from steppes of Central Asia????:

Yes. OK, I'm over-simplying here, for the sake of the story, but this will illustrate the principle....

There's a haplotype..meaning a distinct subset of mtDNA polymorphisms, which is associated with a people called the Sarmatians. The Empire of Sarmatia co-existed with the Romans, in fact the Romans and the Sarmatians fought for hundreds of years. Sometimes one side would win a few decisive battles, then the other side. Well, at some point, the Romans won an important campaign against a Sarmation Lord, and to buy the peace, they demanded that he hand over several thousand of his cavalrymen.

This practice was pretty common.

OK, so what is Rome going to do with a couple thousand trained Sarmatian warriors? Leaving them in Sarmatia would be pretty stupid, bringing them to Rome is asking for an insurrection, so....what? What they did was post the Sarmatians, as Roman Soliders...to the lonely, distant outpost of Gaul.

Which is now the border of England and Scotland.

OK, so take a couple thousand young lads and a few hundred of their women, move them away from their homes and dump them in a new country. What's going to happen?

Imagine how surprised researchers were when they discovered that a whole lot of people from the Scottish Borders share an mtDNA haplotype, AND a few other significant chromosomal DNA markers with peoples from the Steppes of Asia...Uzbekistan, places like that.

Interesting.

[KFCarter]

Thanks all, for this great discussion on DNA testing. I've thought about doing it, but did not really have a clear picture of what it could (and couldn't) provide. Thanks for the education!!

[ForresterModern]

As Alan has said above it was common during the Roman Empire, as well as during the British Empire, for the powers that be to relocate troops obtained in one part of the world to a very distant and often remote part of their empire for their military postings. This has sense, as Alan alluded to, in that locals fighting against local might tend to be less likely to fight a "neighbor or potential relative" of a similar heritage than they would a total stranger in a foreign land with a totally alien heritage. Hence the use of mongol troops to man the frontiers of the britannic roman empire, and the use of Ghurkas as storm troops and military guards by the UK in places across the world but not their own homelands (in general). It makes sense---it is easier to justify fighting against someone who you do not look like, share a common language with, or have any cultural relationship to than it is to fight a neighbor or potential relative to whom you may have more sympathy/empathy. A tactic that has been in use for thousands of years.

This may explain a lot of the aberrancies in DNA testing, as obviously these relocated troups, if left there long enough, would be likely to intermarry with the locals over time, even possibly becoming settled there for the remainder of their lifetimes and thereby become "locals" themselves after a generation or two. That combine with general migration and repetitive warring invasions (e.g., the vikings over virtually all of coastal western Europe) alone would cause such a melange of genetic material that would likely make ones head spin were he to try to make sense of it all in a vacuum.

[turpin]

So how does it work if my Scottish line comes thrugh my mother, her father and grandfather, thence through her great grandmother to her GGM's father and patrilineal from there?

Obviously the Y test isn't right, but will the mtDNA test shed light any better? Or is this a case of "you're hosed, turpin"?

[gilmore]

So how does it work if my Scottish line comes thrugh my mother, her father and grandfather, thence through her great grandmother to her GGM's father and patrilineal from there?

Obviously the Y test isn't right, but will the mtDNA test shed light any better? Or is this a case of "you're hosed, turpin"?

I wouldn't say you're hosed, but patrilineal YDNA and matrilineal mtDNA testing wouldn't be too helpful in your case. Besides, as was noted, since you already have the paper trail to your ancestors, YDNA and mtDNA would not be as useful for you as it would for others who have hit a brick wall and have no idea of where to look next, need help in looking at areas to focus on, and areas where further reserach isn't likely to reveal anything useful.

Our patrilineal and matrilineal ancestry are but two lines that become a smaller and smaller part of our total ancestry as we go further back in time.

There is a third test done in genetic genealogy call autosomal DNA testing. It shows which population groups your ancestors came from, but not how. The results might show that 25% of your genetic makeup matches that of people in the Caucasus mountians, 5% matches Bantus, 45% matches Finns from the southern part of that country, 15% matches Andadusians, 10% matches Westphalians, etc. In other words, it's not usually particularly helpful for genealogical research, but some find it interesting.

(BTW, I am sorry I missed you last Saturday. I was suddenly sick, but am better now. Perhaps we can get together at Fado on a Monday or The Grange in Decatur on a Tuesday before I leave on 9/9.)

[dfmacliam]

So how does it work if my Scottish line comes thrugh my mother, her father and grandfather, thence through her great grandmother to her GGM's father and patrilineal from there?

Obviously the Y test isn't right, but will the mtDNA test shed light any better? Or is this a case of "you're hosed, turpin"?

I would think if you had an uncle or someone from her male line take the test... it will reflect that ancestory

[O'Callaghan]

I would think if you had an uncle or someone from her male line take the test... it will reflect that ancestory

This is similar to my situation. I have two uncles (my mum's brothers) who are the last male O'Callaghans of the name in our family. One never married, and the other married someone who already had a daughter and didn't want more children. They are both well into their eighties, so there's no likelihood that either of them will have a genetic son now.

I would love to know what a DNA test on either one of them would show, but I am hesitant to ask them to get tested. I doubt if they would immediately realise that it would only take a scraping from under the tongue (or so I've heard). OTOH, if it is left too long, then eventually it will be too late, for the saddest of reasons. I think I ought to speak to my mum about this. She is the family genealogist anyway, so she would be interested in the results I'm sure.

The burning question that it ought to answer is whether we are all descendants of Ceallachan of Cashel, King of Munster, d.953, or simply, as we already know, descended from a long line of Irish sailors. Whether a Y DNA test could even answer that I'm not sure, but the only way to really find out is to test one of my uncles.