Help me understand DNA testing

[gilmore]

DNA testing has been commercially available only for seven years or so, but is proving to be a useful tool.

As was pointed out, men inherit Y DNA from our fathers, just as we usually do our surnames, hence that is tested for more often than the other kinds.

The larger the database of results, the more likely one is to match one's DNA with with some one else's. Family Tree DNA at www.familytreedna.com has the largest in the world, and is therefore the most useful. You can test for 12, 25, 37 or 63 markers. 12 is too few to tell you very much, and 63 is more than you need. You can upgrade and test more markers later, since FTDNA keeps the samples for 25 years.

Your DNA may match exactly with that of a man who has meticulous and reliable records going back over a thousand years. Or you may find no matches at all. Or you may find that your matches all hve surnames different from yours and come from the other side of the world than you thought your family did. It's a crapshoot.

Probably the most helpful thing that Y DNA tells you is who you are NOT related to. That is, by showing you who your close matches are, it gives hints as to where research is likely to be beneficial, and where it is likely to be useless.

Another thing to remember is that the results are in terms of probability, and rarely exactitude. That is, you will discover men with whom you have a common ancestor within a range of time, a range of generations.

DNA testing isn't really a substitute for old fashioned paper documentation, but can be a helpful adjunct.

[Rob]

Phogfan86 requested a simple explanation of what DNA testing could tell him about his ancestry. However, most of what has been posted so far (although technically accurate) would most certainly go straight over the head of most 6 year-olds. I hope that the following is helpful.

There are two types of DNA that are used for ancestral testing. These are the non-recombining part of the Y-chromosome (NRY) and mitochondrial DNA (mtDNA).

NRY is passed down the direct male line unaltered apart from rare mutations. Therefore a man’s father will have the same NRY signature as the man himself, as also would his father’s father, his father and so on stretching back a thousand years or more. Testing for NRY will tell you nothing about your mother’s father, or his father, etc. Nor will it tell you anything about your father’s mother’s father, etc.

Similarly, mtDNA is passed down the direct female line unaltered apart from rare mutations. However, unlike NRY, it is also passed on by a mother to her sons, but the sons do not pass it on to their offspring. Therefore a man’s (or woman’s) mother (and her mother, etc.) will have the same mtDNA signature as the man or woman themselves. Testing for mtDNA will tell you nothing about your mother’s father’s mother, or her mother, etc.

This leaves an extremely large part of your ancestry about which neither NRY nor mtDNA can tell you anything at all. If we go back to the great great grandparents level (of which there would have been 16 in total), NRY and mtDNA tests would tell you about just 2 of them, i.e. your father’s father’s father’s father and your mother’s mother’s mother’s mother. This leaves 14 great great grandparents unaccounted for (genetically speaking).

Furthermore, DNA testing on its own cannot identify who the 2 direct line great great grandparents were. For this you will still need reliable family records, but once these two individuals have been identified, you can be sure that they will have the same NRY (direct male line) and mtDNA (direct female line) as you have. This only applies to males, as females do not have any NRY to test in the first place, so they can only trace one great great grandparent genetically, unless they can persuade a brother to be NRY tested.

Often a particular NRY signature is strongly linked to a particular surname if it is a patronymic surname, so it may be possible to tell if you are possibly linked to that branch of the family. I say ‘possibly’ as there are likely to be other branches with the same NRY signature.

DNA testing is probably most useful in determining likely ancient migrations of populations. For this reason, the field of study is referred to as population genetics and requires DNA samples to be taken from a significant sample of a current population. It can lead to some unexpected conclusions. For instance, in Victorian times it was assumed by historians that the ancient Britons were either exterminated, or driven out of what was to become England by the invading Anglo-Saxons. Population genetics studies have shown that this was far from being the case, as only a very small percentage of present day English people are descended from these 5th/6th century Germanic invaders, the vast majority being descendents of the ancient Britons.

I hope that this explanation of the capabilities and limitations of DNA testing has been useful.

[Alan H]

This leaves an extremely large part of your ancestry about which neither NRY nor mtDNA can tell you anything at all. If we go back to the great great grandparents level (of which there would have been 16 in total), NRY and mtDNA tests would tell you about just 2 of them, i.e. your father’s father’s father’s father and your mother’s mother’s mother’s mother. This leaves 14 great great grandparents unaccounted for (genetically speaking).

An excellent point and absolutely correct, thanks for mentioning it.

[wvpiper]

An excellent point and absolutely correct, thanks for mentioning it.

Which was alluded to in this story posted two pages back
http://www.cbsnews.com/stories/2007/...n3334427.shtml

"And that's the rub. This business of genetic genealogy is fraught with limitations. For one thing, it can only provide information about a tiny fraction of our ancestry. Because we get half our DNA from our mothers and half from our fathers, almost all of our DNA gets shuffled and remixed every generation, making it impossible to trace what comes from whom. There are just two bits of DNA that remain pure - the "Y" chromosome, which passes directly from father to son, and something called mitochondrial DNA, which passes unchanged from mother to child.

Hank Greely, a law professor at Stanford University, has studied this new field. He worries that people don't realize just how many ancestors they actually have.

"Eight generations ago both you and I had 256 great-great-great-great-great-great grandparents," Greely points out. "It doubles every generation. So you've got two parents. You have four grandparents. You have eight great grandparents. Sixteen great-great grandparents. And it adds up fast. It adds up so fast in fact that if you go back 20 generations you've got over a million grandparents."

1,048,576 to be exact. And in each generation, DNA testing can provide information about only two of them. "

[Galician]

Academic in the house. Academic cap on. I don't to dash your hopes, or let you risk embarassment, when you drop in for a cup of sugar at the neighboring castle BUT a knight would be considered aristocracy, as opposed to royalty, which is strictly the king's family.

[Pleater]

There are always going to be people with surnames and genetics that don't match - so even if it is possible to trace a family line on paper, the genetic results will sometimes be a surprise.

It has been known for samples to get switched at laboratories, babies to be switched in hospitals, and all sorts of other odd occurrences.

Anne the Pleater :ootd:

[vmac3205]

There are always going to be people with surnames and genetics that don't match - so even if it is possible to trace a family line on paper, the genetic results will sometimes be a surprise.

It has been known for samples to get switched at laboratories, babies to be switched in hospitals, and all sorts of other odd occurrences.

Anne the Pleater :ootd:

Not to mention babies getting switched at hospitals. I swear I can't be related to half my family. I must have been switched at the hospital.

[ForresterModern]

Academic in the house. Academic cap on. I don't to dash your hopes, or let you risk embarassment, when you drop in for a cup of sugar at the neighboring castle BUT a knight would be considered aristocracy, as opposed to royalty, which is strictly the king's family.

Galician

Although the connection is loose, according to family historians :

"BALDWIN III, of Flanders, the Forester, ‘of the handsome beard’, who married the daughter of the Count of Luxemburg. This Forester was a great warrior and defended his Kingdom against the united forces of Emperour Henry, King Robert of France and the Duke of Normandy. He died in 1034 and was succeeded by his son:

6. BALDWIN IV, the Forester, called ‘LeDebonair’, who married Princess Adela, daughter of Robert, King of France. They had four children:

7. i. Baldwin V, the Forester

8. ii. Robert Forester, who conquered the Principality, Frisland.

9. iii. Matilda (or Maud) who married William the Conqueror.

10. iv. Sir Richard Forester, (sometimes Latinized, Ricardus Forestarius.)

10. SIR RICHARD FORESTER, mentioned above as the first to naturally bear the name, was head of the powerful Northumberland family of Foresters. "



Sir Richard Forrester was brother in law to William the Conqueror and reportedly his right hand lieutenant in William's conquest which extended north to about the Firth of Forth. Interestingly Corstorphine, parts of the Stirling region, and Northumberland were in some fashion seats of power for the Forrester clan from then on, with a disproportionate distribution of Forresters/Forsters/Fosters represented there in old and recent census data.

If you note more than one "Forrester" married royalty (Baldwin III to the daughter of the Count of Luxembourg, his son Baldwin IV to the daughter of the king of France, and their daughter Matilda to William the Conqueror). There are supposedly several other reports of male branches of the Forrester line marrying into various branches of a couple of the other historically royal bloodlines:

"18. SIR REGINALD who fought at Bannockburn in 1314. A number of his descendants were great chieftains, many being knighted, and were closely related to the Royal Families of England, Scotland, Wales, and Ireland. "

As I said above I am still verifying the american lineage to the English/Scottish lineage, but feel confidant that I am only a year or less away from completing that task. DNA may be the final arbiter one way or the other, however. The knight to which I originally referred was a Sir Richard Forster who allegedly came to america in the early 1600's, landed and was "landed" in Virginia and begat the vast majority of the Forster/Foster families and descendants of those families that originated out of Virginia, one of which we believe to be mine. I am only a couple generations away from making my connection to the Old Country through Sir Richard (lineage verified back to the mid-late 1600's in the appropriate counties in Virginia).



We now return to your regulalry schedule broadcast.

[Galician]

Galician

Although the connection is loose, according to family historians :

"BALDWIN III, of Flanders, the Forester, ‘of the handsome beard’, who married the daughter of the Count of Luxemburg. This Forester was a great warrior and defended his Kingdom against the united forces of Emperour Henry, King Robert of France and the Duke of Normandy. He died in 1034 and was succeeded by his son:

6. BALDWIN IV, the Forester, called ‘LeDebonair’, who married Princess Adela, daughter of Robert, King of France. They had four children:

7. i. Baldwin V, the Forester

8. ii. Robert Forester, who conquered the Principality, Frisland.

9. iii. Matilda (or Maud) who married William the Conqueror.

10. iv. Sir Richard Forester, (sometimes Latinized, Ricardus Forestarius.)

10. SIR RICHARD FORESTER, mentioned above as the first to naturally bear the name, was head of the powerful Northumberland family of Foresters. "



Sir Richard Forrester was brother in law to William the Conqueror and reportedly his right hand lieutenant in William's conquest which extended north to about the Firth of Forth. Interestingly Corstorphine, parts of the Stirling region, and Northumberland were in some fashion seats of power for the Forrester clan from then on, with a disproportionate distribution of Forresters/Forsters/Fosters represented there in old and recent census data.

If you note more than one "Forrester" married royalty (Baldwin III to the daughter of the Count of Luxembourg, his son Baldwin IV to the daughter of the king of France, and their daughter Matilda to William the Conqueror). There are supposedly several other reports of male branches of the Forrester line marrying into various branches of a couple of the other historically royal bloodlines:

"18. SIR REGINALD who fought at Bannockburn in 1314. A number of his descendants were great chieftains, many being knighted, and were closely related to the Royal Families of England, Scotland, Wales, and Ireland. "

As I said above I am still verifying the american lineage to the English/Scottish lineage, but feel confidant that I am only a year or less away from completing that task. DNA may be the final arbiter one way or the other, however. The knight to which I originally referred was a Sir Richard Forster who allegedly came to america in the early 1600's, landed and was "landed" in Virginia and begat the vast majority of the Forster/Foster families and descendants of those families that originated out of Virginia, one of which we believe to be mine. I am only a couple generations away from making my connection to the Old Country through Sir Richard (lineage verified back to the mid-late 1600's in the appropriate counties in Virginia).



We now return to your regulalry schedule broadcast.

Not to get into a huge debate, but as I stated before, counts would be aristocracy, not royalty.

Two further points, just for the record, in researching the Counts Baldwin, according to Wikipedia:

A) Baldwin III died in 962 and was succeeded by his son, Arnulf II.

B) Arnulf's son, Baldwin IV, begat his son and successor by his first wife, Ogive, daughter of the Count of Luxembourg. Later he was married to Eleanor, daughter of Richard II, Count of Normandy.

C) Baldwin V married Princess Adele of France in 1028. (So this is where a royal connection does indeed enter the family.) This Baldwin was the father of Mathilda, who married Count William of Normandy, who went on to become King of England.

Here endeth the lesson.

P.S. An interesting footnote perhaps. Do we remember that the major reason for William's Conquest was that King Harold Godwinson's army was exhausted from a previous battle? If not, let me remind people that the English army had just fought off a Norwegian force on the northeastern coast of England. Just days later, William's forces landed in the south. One of the two leaders of the Norwegian invasion was married to Mathilda's aunt, daughter of Baldwin IV. Ah, family!

[ForresterModern]

Not to get into a huge debate, but as I stated before, counts would be aristocracy, not royalty.

Two further points, just for the record, in researching the Counts Baldwin, according to Wikipedia:

A) Baldwin III died in 962 and was succeeded by his son, Arnulf II.

B) Arnulf's son, Baldwin IV, begat his son and successor by his first wife, Ogive, daughter of the Count of Luxembourg. Later he was married to Eleanor, daughter of Richard II, Count of Normandy.

C) Baldwin V married Princess Adele of France in 1028. (So this is where a royal connection does indeed enter the family.) This Baldwin was the father of Mathilda, who married Count William of Normandy, who went on to become King of England.

Here endeth the lesson.

Guess I should be wearing my asbestos kilt right about now. Thank you for your kind and gentle corrections to some of my statements, but as I said they were based on "family histories", which are as much if not more prone to factual errors as are the listings in Wikipedia sometimes. Key point: potential royalty relations as described above and graciously acknowledged by you.