Q1. What is this DNA test all about?
A. There are two types of DNA tests now available for genealogical testing: the
Y-chromosome (Y-DNA) test and the mitochondrial (mtDNA) test. A direct female
line can be traced by testing mitochondrial DNA. However, since we are presently
interested in tracing surnames, which are usually passed from father to son, the
testing of the Y-chromosome DNA is what we are interested in. For more
information on DNA and Y-chromosome testing see DNA
101.
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Q2. Will a DNA test tell me who my ancestors are? What
will the test tell me?
A. No, a DNA test will NOT tell you who your ancestors are. The test WILL
tell if two or more participants share a common ancestor, and give you a
probability of the number of generations to the The Most Recent
Common Ancestor (TMRCA).
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Q3. Why do we analyze the Y chromosome?
A. The Y chromosome is the only chromosome passed unchanged from father to
son, and therefore indicates the paternal line of descent. All males in a
patriarchal line have the same Y chromosome. The Y chromosome is not
present in females. For more information on DNA and Y-chromosome testing
see DNA 101.
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Q4. What is analyzed?
A. We look at specific parts of the Y chromosome to obtain a “signature”.
Two or more males whose Y chromosome signatures match come from the same
paternal line of descent. Those whose signatures do not match are from
different lines. For more information on DNA and Y-chromosome
testing see DNA 101.
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Q5. Exactly what does a Y chromosome match demonstrate?
A. A Y chromosome match shows that two males have a common male ancestor.
This ancestor could be their father, or it could be a male from
a thousand years ago. For more information on DNA and Y-chromosome testing
see DNA 101.
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Q6. Does a Y chromosome match prove this relationship?
A. Although no evidence is ever absolutely certain, the confidence level for
such a match is very high. Typically, there is less than one chance in a million or more that the demonstrated relationship is in error.
For more information on DNA and Y-chromosome testing see DNA
101.
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Q7. What is
the advantage of the 25 marker test over the 12 marker test?
A. More markers reduce the number of generations to the The Most Recent
Common Ancestor (TMRCA). If you match someone on 12 out of
12 markers you almost certainly share a common ancestor. The question becomes "how far back do you have to go before
you find that common ancestor?"
If all 12 markers match there is a 50% probability that TMRCA is 14
generations or less, a 90% probability that TMRCA is 48 generations or less, and
a 95% probability that TRMCA is 62 generations or less. For 12 identical
markers, 95% of the possible TRMCA values fall between 1 and 77 generations.
If all 25 markers match there is a 50% probability that TMRCA is 7 generations or less, a 90% probability that TMRCA is
20 generations or less, and
a 95% probability that TRMCA is 30 generations or less. For 25 identical
markers, 95% of the possible TRMCA values fall between 1 and 44 generations.
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Q8. Do Y chromosome analyses sometimes match, but not at every
point?
A. Yes. Over a period of many years, a small number of mutations can be
counted on to appear, so there may be one or more
points where the Y chromosome analysis does not match exactly. For more
information on DNA and Y-chromosome testing see DNA
101.
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Q9. If no Y chromosome match is found, what does that
show?
A. It demonstrates to a very high degree of probability that the two males
analyzed do not share a male ancestor. Although this is true for the two
individuals tested, it may not be true for the family groups of the
individuals who were tested, because there are a number of sources of “non-paternal
events”.
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Q10. My maiden name is BLAIR and I would love to have this
information, but I am female and have no brothers
and my father has passed on now. There are
no living males with surname BLAIR in my family, only male cousins named
BLAIR, some quite distantly related.
A. Your male cousins probably have the same Y-DNA as your father and his male
ancestors with surname BLAIR. Testing your cousins is the same as testing
your late father if they are the natural children of your BLAIR ancestors.
That is because the Y chromosome passes unchanged from father to son apart from
random mutations. So if your father and your cousins have any known common
ancestor, even back to your 4th great grandfather or beyond, the DNA sample
should be the same as testing your father, give or take a mutation or two.
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Q11. My line split off from the BLAIR family two hundred
years ago. My ggg-grandmother was a BLAIR.
I do research on my BLAIR ancestors but have no close
BLAIR relatives.
A. If you know or can find male surname descendents of your gggg grandfather BLAIR, you can in effect “test” him by testing his descendents. That is
because the Y-DNA is passed on without change from father to son. If you
test a couple of your BLAIR cousins and they match, you can say with high confidence
that their Y-DNA is very close to the Y-DNA of your gggg grandfather.
Then you can compare his sample to other samples in the study and possibly learn
much new information about his line for your research.
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Q12. Why are you excluding
women? We are the children of our BLAIR ancestors
as much as the men.
A. We cannot test females for the Y chromosome because they do not have
one, only males. The technology does not exist to trace BLAIR surname ancestors
through their female descendents, at least not yet. The reason requires
going into a bit too much explanation of basic genetics, but essentially we
get a blend of genes from our fathers and mothers for everything except the
Y chromosome, which passes mostly unchanged from father to son. Most other
genes combine, thus making every individual unique with a unique genetic signature.
But that does not mean that daughters are not just as related to their fathers
as sons. In fact everyone has genes from all their ancestors, half from
each parent, a quarter from each grandparent, an eighth from each great grandparent
and so forth back forever. Every gene in our DNA existed in some ancestor 10,000
years ago apart from a few mutations possibly. By using Y-DNA analysis
women can learn much valuable information about their BLAIR ancestors, the same
as male descendents. There are tests of mtDNA that trace female lineages,
but they are not useful for single surname studies.
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Q13. There is only one living male person surname BLAIR in
my family. Is there any point joining the study
if I don’t have two or three family members who
are BLAIR surname males?
A.Yes, there is potential value for you to join the study. The reason
for testing two or three distantly related cousins is that this “validates”
the family at least back to the known common ancestor. A single test could provide
incorrect data for the family if there is an unknown adoption or a false paternity
somewhere back in the past. If you alone take the test and it matches
others in the study, you will have learned that your branch of the BLAIR family
is related to theirs, with little doubt. If it does not match and you
cannot find any cousin to test to validate the result, at least your sample
will sit there in the database until sometime in the future a match is secured.
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Q14. I was adopted by BLAIRs as a child. Is there any benefit to do a DNA test?
A. That depends on whether you are trying to trace your "biological"
family or your BLAIR family. If you're trying to trace your
"biological" family you would have your own DNA sample tested.
If you already know the surname of your "biological" family, it would
probably be best to try to find a DNA project for that name since your results
would more likely match someone in that group than the BLAIR group.
If you're interested in tracing your BLAIR family roots you would need a DNA
sample from your BLAIR father or other male BLAIR family member.
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Q15. My male BLAIR cousins don’t care a thing about family
history. They won’t pay for this.
A. There is no rule that says the person ordering and paying for the test must
be the person being tested. If your cousins will consent to doing this
simple, painless test, you can order the kits on line and then send them to
your cousins, and return them with your own payment. Some of the other family
reconstruction projects have multiple researchers in the same family line that
have split the cost of testing male cousins who have no interest in our hobby.
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Q16. I already know my BLAIR family comes from somewhere
in Ireland. What are we going to learn from
doing this that is new?
A. First of all, you may discover many BLAIR families that are your cousins that
you did not know about before. They may have new information and family
histories that will be useful to you, and you will know they are your relatives
with little or no doubt. A couple of families named BLAIR side by side in
the census could be brothers, or could be coincidence. But DNA is proof.
Second, as the study expands over time, you may discover the exact village where
your ancestors came from in Ireland, possibly even Church records that take
you back hundreds of years.
You may also discover that you share the same markers with BLAIRs who come
from Scotland. There are people who believe that the BLAIRs who came from
Ireland originated in Scotland but for many who have gotten back to Ireland they
are not able to make a Scotland connection. DNA testing might make this
connection.
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Q17. All it takes is one break a long time ago and you
won’t be able to match up a whole line of BLAIRs.
You will never be able to put all the BLAIRs together.
A. That is very likely true, but the purpose of this is to help different BLAIR
families link up to further their genealogical research. Even if long ago
a Mr. BLAIR adopted a boy whose natural father was Mr. JOHNSON, all his male descendents
will still be with a common ancestor, which may prove useful. Also, if someday
a JOHNSON has a test done, we may find that match as well!
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Q18. How is the DNA sample obtained?
A. DNA can be obtained from any cell, but one of the easiest samples is
obtained by swabbing the inside of the cheek with a sterile cotton swab.
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Q19. How do I participate?
A. Details on how to participate will be provided if the BLAIR DNA Project gets
off the drawing board. Basically each participant will fill out an Application
Form and a Pedigree
Chart which will be sent to the Family Coordinator. The Family Coordinator
will assign each participant a unique Participant ID# and send the participant a
DNA sample kit. The participant will take his own DNA and return it to the Family
Coordinator along with a check payable to the Testing Lab. The Family
Coordinator will forward the DNA to the Testing Lab. Results will be returned to
the Family Coordinator who will forward them on to the participant.
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Q20. How will my DNA information be used?
A. This poses a declicate balance between making the information available to
others while protecting the privacy of the participants. DNA test results are of
little use on there own. Their value is how they compare to other test results
and who they match. Most other surname DNA projects display test results on a
website as shown below:
| Marker |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
11 |
12 |
|
| |
DYS# |
Part
ID# |
3
9
3 |
3
9
0 |
1
9
* |
3
9
1 |
3
8
5
a |
3
8
5
b |
4
2
6 |
3
8
8 |
4
3
9 |
3
8
9
i |
3
9
2 |
3
8
9
ii |
Ancestor
# |
| 3947 |
13 |
26 |
14 |
11 |
12 |
14 |
12 |
12 |
11 |
13 |
13 |
29 |
0001 |
The numbers (1-12) across the top of the table
are the marker numbers. They have no significance other than as an
easy way to refer to the marker. Note: FamilyTree DNA refers to these
numbers as Locus. The second set of numbers across the top of
the matrix are DYS# (the actual marker names).
The numbers down the left side of the table identify
the participant in the DNA project.
The numbers down the right side of the table identify the participant's
oldest known ancestor.
The rest of the numbers are the Allele (the number
repeats) for each participant at the specified marker.
Note that there is nothing to identify participants other than
the participant number.
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Q21. How will my DNA information be protected?
A. Only the participant providing a DNA sample and the Family
Coordinator will know what his results are (unless they decide they would
like to share that information - see next question).
All samples and identifying information will be received by the and will be assigned an identifying number.
This ID number will be the only identifying information anyone else
sees, so no one other than the coordinator will know who participates in
the study or which result is from which person. The portion of the DNA
tested gives a distinctive "signature" for a lineage rather than for an
individual, so there is no risk of this data being of any use to anyone
for personal identity.
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Q22.
I noticed my DNA markers match those of several other participants. Is there
anyway I can contact them?
A. If the participant chooses not to identify himself, you can contact the Family
Coordinator who will forward your request on to the participant.
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Q23. Couldn’t it be embarrassing if an individual’s Y
chromosome does not match when it should?
A.
Yes, and for this reason no participant's results will ever be revealed except
by a code. Names of participants will not be published or released unless the
participant give his WRITTEN permission to do so.
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Q24. My test results do not match any others, does that
mean I'm not a BLAIR?
A. There is always a possibility that you could get disappointing test results.
Samples that vary by three or more markers from the main group may do so for a
number of reasons. One possibility is that they represent distinct lines either
older or younger than the currently observed most frequent line. Another is that
there has been a “non-paternal event” at an unknown past time. There are
several possible types of non-paternal event in addition to a pregnancy gained
outside of a marriage. For example, a child may be adopted and given the BLAIR
name; a man may take the BLAIR name when he marries a BLAIR daughter; a BLAIR
man may marry a pregnant woman whose husband has died; a couple where the wife
is the BLAIR may choose to give their children the BLAIR name for various
reasons; clerical error in recording administrative data may assign a BLAIR name
to the wrong person, and so on.
It should be stressed that adoptions were quite common in every age (ie. parents died by disease or war and a relative took in the children and
raised them with their name; or young daughters had a child out of wedlock and the parents raised it as their own).
Some may not want to see a result indicating a non paternity event but we are all legal
BLAIRs and a small sample size could be misleading. One may get a DNA sequence which suggests a non paternity event but they could be of the original blood
BLAIR line. Let me explain. Twenty people are tested and 19 are very similar but the last is clearly different. It could turn out that the 19 descend from the same
person 300 years ago and this person was an adopted BLAIR while the other is of the original blood line going back 800 years.
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