Common Questions About DNA Testing for Genealogical Purposes
including some common misconceptions
In my observation of DNA testing among the Yancey Family - I
often find that people purchase and use a
genealogical DNA test - -
often without even really knowing what to expect – or without having a
specific goal or item to prove/disprove. Also
just purchase the most commonly available test or the cheapest
test (such as ancestry.com)
– having no clue how it might be different if they used a different
company or different test type. Knowing what your goals are
testing and becoming familiar with the different tests and which
companies provide each test – can make the difference between you
reaching your goal – and you just wasting your money.
people have misperceptions about DNA testing and how to interpret DNA
results - below are some discussion of common misperceptions.
WHAT ARE THE DIFFERENT DNA TESTS
AND DOES IT REALLY MATTER WHICH TEST AND WHICH COMPANY I USE?
(Paternal Line) DNA testing is used to test the DNA that men
inherit (near perfectly) from their Father (and thus from their
line direct male ancestors). These results can then be
another male who has been tested to see if the results indicate
a match (near
match). Any results can be matched with other testers
resulting in a statistical probability that they have a
common male ancestor on their paternal line. Matches within 8
generations or so are pretty black and white would have a very high
Who would choose this type of test?
main purpose of a YDNA test is to prove that two testers have a common
paternal line ancestor – and since surnames are usually carried on the
male paternal line – it is often referred to as the DNA for that
surname. The test can only be
done on males. It was this test that first proved that the
and the Nanney family do not have a common male ancestor – biologically
speaking – because the YDNA of Yanceys and Nanneys was drastically
different (even different haplogroups).
This test usually costs about $150 - varying from
one company to the next as well as the number of markers tested.
ANCESTRY.COM – has NOT provided YDNA testing for quite some
I suggest the use of Family tree DNA for this test (for the
main reason – that so many other Yanceys have also used this
company – and you will be able to directly compare against
results - - which might not be possible if you use a different company)
To see the results of various Yanceys (and Nanneys and others) who have
taken the YDNA test
See this page and test result (be sure to note the
scroll bar in the result window)
that when we say "paternal line" we are only talking about
individuals who make up the link as we go on a pedigree chart
from son to father, to grandfather ad infinitum. . .
. (with a male ancestor at every single link)
It does NOT mean all the ancestors/DNA of one's father. Every
single person in this ancestral paternal line link must
be male - if it were not so - the YDNA would not have been passed down.
Persons who do have common Paternal ancestry within
recent centuries - will have a virtual match. People who may
related, but not via the single paternal line, but
other line will NOT have a "sort of match" - rather they will
have a total NO Match. Within recent centuries the indication
common paternal descent should be either black or white (yes or no).
YDNA Success Story
Results of Yanceys tested with YDNA test kit (note scroll bar in window)
DNA Testing for Genealogists - a great video
DNA testing (Maternal line testing) is very similar to the
YDNA(Paternal line) test – except the mtDNA test is based on DNA passed
(near perfectly) from Mother to child.
who have a match on mtDNA have a common maternal line
ancestor. (mother of their mother of their mother .
) Both Males and Females can take this test.
ANCESTRY.COM – has NOT provided this test option for quite some time
Who would choose this type of test?
surnames don’t (normally) get passed down along the maternal line – the
mtDNA does not normally apply to a specific surname. Also due
how rare mutations are in the mtDNA - a common maternal ancetsor
between two matched people - could actually be an ancestors a thousand
years ago. For these reasons this test is normally much less
in the area of genealogy. Though if the goal is to prove
maternal line of descent – the test is very conclusive.
Note that when we say "maternal line"
we are only talking about
the individuals who make up the link as we go on a pedigree chart
child to mother, to grandmother ad infinitum. . . .
(it does NOT mean
all the ancestors/DNA of one's mother) - and every
person in this ancestral link must be female.
many company’s may use different names for this type of test
(such as “Family Finder” or other names ) - - this type of
is based on a genetic testing known as autosomal DNA
testing. The most common Autosomal tester is
ANCESTRY.COM - and for some time now it has been the ONLY test
Contrary to YDNA and mtDNA (which are tests that
apply to a SINGLE line of descent paternal/maternal) - - the autosomal test
apply to DNA inherited from your ancestors as a composite
whole. The autosomal test is often provided with
that attempt to indicate percent ethnicities or percent countries of
ancestral origin. Though the truth is such results are often
in way that is often misleading and even on the verge of
untruthful. One has to use real caution in interpreting
Even though the enthnic reporting provided can be of limited value
- - there are still some significant reasons one may wish to take an
autosomal DNA test. One of these reasons is the ability for you
to find DNA matches between you and other testers that indicates a
common ancestors. Matches between two people based on autosomal
testing – are pretty reliable as to the fact that a common
ancestor/family line exists between such testers.
HOWEVER - the test itself – does not explicitly
specific LINE/ANCESTOR the common match is originating from. To do this
requires additonal detective work.
DNA companies supplement this autosomal DNA match with genealogical databases that
attempt to show where in the family tree the common ancestral line is
However such genealogical databases may either be
imperfect/incomplete and may not go into time periods where the match
actually occurred. It is quite possible that two people
may make incorrect assumptions as to who the common ancestor
is or they may not be able to determine exactly which surname is the common link.
Who would choose this type of test?
People would choose the autosomal test if they want to get some idea of
ethnicity/geographic components though such results are
near perfect – and do not normally contain any “time factor”
what point were my ancestors among this ethnic group or this geographic
region?) Also people very often mistakenly assume
much applies to their surname line – when in reality it is a composite
of all of their ancestors (of which their surname line – is
one of millions of other family lines they descend from).
fact is - most people already have a pretty good idea as to
general ethnicicty background - and the ethnicity test result may not
tell them much than what they already knew. However DNA companies
will also provide mathing DNA reports - showing what other testers you
"match" with - and allow you to make contact with these matches.
This is one of the main reason to take autosomal DNA testing.
People might also take
the autosomal test because they are looking for a match between
two family groups – that DONT share a YDNA/mtDNA link - - but
suspected to be related via some other line in the family tree
(other than the paternal or maternal).
Autosomal testing is less restrictive than the YDNA. mtDNA tests
(a generally good thing) - though the results may be more ambiguous
(a bad thing).
autosomal test usually costs about $100 - and is usually the
cheaper test that people may find in their on line searching.
But make sure it is right for you - or you may find it didnt help you
accomplish your goal and you might have to retake a different test.
Some Peoples experience with autosomal testing:
DNA Success Stories
Tips on making contact with autosomal matches
With both YDNA and mtDNA
testing - - - testers are usually categorized into one of
a small set (less than
25) of what are called “Haplogroups” – which attempt to show
different branches of the genetic branches of human descent (an
extremely high level view of the world family tree).
People with the same Haplogroup – would have a common ancestors at a
much nearer distance – as compared to people who have two different
But scientists believe haplogroups trace back THOUSANDS
of years - - so one should NOT assume that such common haplogroups and
corresponding geographic regions shown in test results based
Haplogroup represent where their immigrant ancestor
directly came from when arriving in America. In other words
map showing your Haplogroup concentrated in the area of what
Turkey - does NOT mean your ancetsor who immgrated to America 200 years
ago came from Turkey. And it might not even mean that any of your
line ancestors lived in Turkey - since most Haplogroup charts
are based on results of people who CURRENTLY live in a given
(most charts dont take into consideration human migration
the centuries and millennia)
Also note it is a different set of Haplogroups for YDNA versus mtDNA
people will use DNA testing to find "cousins" who they match with.
This will often be the most common reason for DNA testing. Its
may find cousin matches you would not have found elsewhere.
BUT don't think DNA testing is the necessarily the best or
quickest ways to find cousins. There are certainly many other means to
find relatives these days - especially with the use of the
Internet. Though it is true that DNA matching may/can put you in
contact with various people you would not have found in more
traditional means - it is not a silver bullet. Also of note
that even though some DNA company may give you pages of
"potential matches" - it is quite possible that you may not
success in trying to contact many of the persons on your match list.
And even if
you do - - the location on the family tree of the exact connection may
be totally uncertain. each person's experience with DNA testing
will be different.
Tips on making contact with autosomal matches
WHICH COMPANY TO USE?
people just compare the cheapest prices among differnet DNA testing
companies and select the cheapest. People often choose
Ancetrey.com due to lower cost. But all too often they later
realize that the test they took - wasnt the the test they really needed
to take - to find out what they were trying to discover. And
they have to pay more money for a different company to do a different
Understand what your goals are before ordering a test.
Sorting out the DNA Tests
makeup - some helpful metaphors
analogy/metaphor that I really like to use when discussing
DNA that we inherit from our ancestors - is to compare it to
very very large ROPE of many different (millions) of colored small
individual threads. Each thread has its own unique
color/character. But the rope as a whole has its own unique
characteristics. I realize that often metaphors
perfectly match reality – and this is no exception. But the
emphasis here is that we are all the product of millions of different
ancestors/family groups. As a sample scenario -
often quick to take the Ancestry.com DNA test - - and then
they get their results - - expect that it applies to their
Surname family line ("The Yancey Family"). The truth is our
surname line is only one of millions of family lines – and as
the DNA we would inherit from some immigrant Yancey ancestor as an
example – would only be one of many thousands of ancestors and thus
would only make up a very small percentage of our DNA (less
1%) - -- thus Autosomal results cannot apply to any single
family line - - -they apply as composite info – as to your family tree
as a whole.
to consider. Though I really love this
metaphor of a rope with threads for each family line - - as our DNA
inheritance - - it should also be noted that even
siblings with the same exact mother and father – the threads and
composite ”rope” each child inherits are NOT
(that’s why one sibling can look very much different than another
sibling). Though each of a set of siblings inherits
their DNA from their father and 50% from their mother - -
NOT inherit exactly 25% from each grandparent. It’s a random selection
from the grandparents DNA that was pased on to the parent.
going back to the rope metaphor - - each child will have different size
threads or maybe better stated – a different sub-set of threads than
what other children inherited from their parents.
As a result of what was
just stated - - one must realize that DNA testing results in the
autosomal test (even if perfectly accurate – which they are
– DO NOT actually represent the accurate family
tree of the
tested person as shown on their pedigree chart.
represent the DNA/Genetics that the tester actually DID inherit from
their ancestors (or not) - and thus the actual
– may not match (will not match) the results if the person
inherited DNA from all of their ancestors in a perfectly equal
portion. Descendants don’t actually inherit DNA from their
ancestors in perfect equalk proportion - - though the
over time and people – may correspond to the stated
expectation. This is one reason that one family
actually have a small portion of Native American ancestry -
- and yet one child may show it in their results and another
child not. Autosomal results among siblings are not
identical. Contrastingly YDNA results among male
would be near identical, as well as mtDNA results. (the latter two only
NOT being perfectly the same – under the case of random mutations that
can rarely occur between Parent and child)
Here is an interesting discussion:
For more details: about genetic testing you may
wish to visit these sites:
Some common misperceptions about DNA testing:
#1 DNA Tests are expensive.
Answer: It depends
is a relative term. DNA tests can start at about $70 and go up to about
two tests that have a significant price difference - are normally two
different test types - with valid reasons for price difference.
Things that control price usually include test type, and numbers of
markers tested. I do not recommend people simply start with the
cheapest test and see how it goes. Nor do I recommend people take
DNA test simply because "everyone is doing it". I recommend that
people take a test after analyzing the different types of tests that
available and see which one best meets their goal - which may not be
the cheapest. And if they don't have a specific goal in
mind - - then I
question if they should really be taking the test.
Selecting the cheapest test for no other reason than price -
may simply be a waste of money.
#2 Genealogical DNA tests are the same thing as what you see that CSI Investigators use.
DNA tests are not the same as the type of tests used by CSI
investigators. Genealogical DNA tests use a mouth swab to gather
DNA sample - and DO not use things like blood, hair or tissue
samples. Genealogical DNA tests are for the living (not the
dead) and are used to help indicate common ancestral lienage
between two testers.
Since certain types of DNA are passed down from parent to child
near perfect replication - we can indirectly know the DNA type
of some of our deceased ancestors. CSI type DNA tests
are usually much more expensive. Paternity testing is also not
exact same thing as genealogical testing - though similar.
#3 DNA testing will open me up to identity theft or "Big Brother"
Answer: Far exaggerated.
general impression of people that have this line of thought is that
they are far exaggerating possible negative implications of DNA
testing. Identity thieves and related malfactors often use things
SSN's, birthdates, credit card numbers and similar items to steal
identities. Such information is either not gathered at all by DNA
tests, or in the case of credit cards is not normally kept on
In my humble opinion people are thousands of times more likely to
experience identity theft by simply using a credit card in a
restaurant, than they are by doing a DNA test. The results
genealogical DNA test - would be of no significance to an
theft. Also the government and big brother do not own these DNA
companies. And one should realize that even if we submit a sample
DNA testing - in most cases we are still in control of our sample
and can have it destroyed upon request. Just like money in the bank
still in our control - our DNA sample is still in our control.
one possible negative impact that can take someone totally by
surpriseand that many people dont consider - are DNA test findings that may indicate something that was
totally unexpected. For example - the discovery that a given person was not the
biological child of the parents assumed as biological parents. It can be a total shock to a tester.
#4 DNA testing will allow me to more fully fill out my family tree chart.
Answer: FALSE and TRUE
speaking - NO, a DNA test, by itself, will not provide the names for your
ancestors. BUT because of the things that are revealed - and
information about people you match with, coupled with information
gathered through genealogical research- a DNA test can indirectly
provide clues that do help you find the identity of your ancestors.
BUT genealogical DNA testing is NOT a silver bullet that magically
fills out your pedigree chart all by itself.
#5 - It is easier (& less costly) to prove that two people are not related than to prove they are related.
- TRUE. Case in point was the 2013 DNA testing that was done
between members of the Yancey Family and members of the Nanney Family
- with a simple 12 marker YDNA test (I think it was
only about $50 per test). As a result of this test - it was
easily discovered with little cost - that the Yancey and Nanney
male line descendants do not share the same Haplogroup (DNA
Grouping) Yancetys were J2 and Nanneys were R1. Based solely on
this simple discovery it was conclusively ascertained that the Yanceys
and Nanneys tested do not share a common paternal line ancestors within
recent centuries. However to prove that two people do share a common
ancestor would take a comparison of more DNA markers (preferably at
least a 37 marker test ) and a near match on all 37 markers.
#6 - DNA Testing will tell me what country or region
my immigrant ancestor
Though autosomal testing may give you some general ideas at a
very high level what region of the world your ancestors (as a whole)
may have come from (using
probability statistics) .
They cannot tell you what country one specific American immigrant came
from or even one ancestral line. Many Americans actually have
hundreds or even thousands of
immigrant ancestors - -each one with only a minute portion of their DNA
being found in the currently living descendant (if any at
DNA doesn't respect political borders. People born in a given
country - dont magically get endowed with a certain set of DNA. Though
it may be true that certain DNA types are found with prominence within
a given country or region. But as a person or family migrates from one
country or region to another - its not like their DNA changes to match
the region. There is no way that DNA can prove or
control - - where a specific given ancestor lived. Though it
might be true that we can use probability and statistics to come up with
a probability that our ancestors came from a certain region - the rules
used in such analysis are very imperfect and are inconsistent from one
company to another.
Most DNA ethnicity reports don't take into consideration human migration
and changes in political borders over time. Actually what
many people dont realize is that these ethnicity reports are
normally based on comparisons to DNA tests of LIVING people around the
world - whose DNA results have been stored in a large database and this
database used to generate DNA ethic groupings. But where
these people live today - may be totally different than where there
ancestors lived 500 years ago. There have been over time -
many major migrations - not all of which are well documented.
A given single family line - might trace from the area of
the Middle East, to France, later Britain, then America and
maybe even later Canada. How does this get reflected in the
ethnicity reports?? (It doesn't)
Note that even among siblings - who have the same mother and
father - there can be significant differences as to Autosomal
DNA Ethnicity reports. Some people have claimed as much as a
10% difference in percents among siblings tested. Thus any
percent less than like 10% could simply be due to sibling variance -
and may not reflect the true percentage of a family pedigree.
This is mainly because though siblings inherit DNA
from the same parents at 50% each - it is not the same
50%, but a randomly selected different 50% for each
child - thus each sibling will inherit differing portions of
DNA from the four grandparents. And there will be some DNA in
each ancestor - that just never makes it from grandparent to a
Because only certain DNA is passed from one generation to the next - -
the DNA that a descendant inherits is not an equal proportion of all
their ancestors. There may be ancestors who's DNA footprint in a given
descendant is so small it is effectively non existant.
Autosomal DNA testing will only show porportions of Ethnicity
based on DNA that was actually inherited. This is why even if
a person had 1 Grandparent with 100% British DNA, and another with
100% Scandinavian DNA, and another with 100% Russian,
and the last with 100% Asian - - - if autosomal testing was
done - - chances are low that they (the grandchildren) would report
exactly 25% of all of these ethnicities. And if there
were siblings - each sibling would report a unque
set of percent ethnicities.
Note that there is no time frame given the autosomal DNA reports as to
what time period ones ancestors came from a specific region or
ethnicity. Was it 50, 100, or 1000 years ago that my
ancestors lived in these regions?- DNA tests would not normally have
any time factor - and without the time factor - - their use for
genealogical purposes becomes very limited.
Note that even if a DNA Testing company reads your DNA markers with
100% accuracy - which probably isnt that far off from reality.
Even so - that doesnt mean that the inferred results of those
markers will be interpeted the same by differing companies.
Such is especially true of autosomal ethnicity reports.
There is nothing on your DNA that yells out "Hey - I am
Irish DNA, or I am African DNA" - there is no golden standard of rules
that companies must follow to derive the ethnic percentages from the
known DNA marker values. For this simple reason - differing
companies can give differing results on the ethnicity of your DNA - even
if they both read your DNA markers with perfect accuracy.
Interestingly even with the same company you can get
different results on subsequent testing and is probably mainly
due to the the fact that simply their subjective and imperfect
rules have changed for how to interpret results. As the databases of
DNA companies get bigger - and the rules they apply become
more complex - - the results they report - even on the same DNA sample
Not all companies use the same granularity as to DNA ethnic origin.
For example some companies may simply divide the African
continent into various regions - while other companies might
try to use the granularity of current political boundaries of
African nations (which didnt even exist
politically speaking 200 years ago). Don't just assume that
because one company reports a more specific location means that the
report is more accurate - - it actually may be the contrary.
Be extremely cautious when geographic statistics of origin are used on
YDNA or mtDNA results or haplogroups (versus autosomal)
- since such results only apply to one ancestral
line among thousands or millions. People
are the product of all their ancestors - not just the paternal or maternal line.
Realize that many news stories are more hype than fact - - such as news
stories about test-takers such as Oprah Winfrey learning she is Zulu or
a Floridian accountant being told he descended from the Mongolian
warlord Genghis Khan.
so often people think "oh that's cool that I have these percentages of
ancestral origin" - - - but in the end - - virtually
nothing comes of it in the long run (or even the short run) as to
making any genealogical progress. And oft times its nothing they didnt
really already know for the most part.
I do believe there are
some very legitimate cases for taking autosomal DNA testing -
but be cautious in the inepretation of your results.
Autosomal Testing can provide some cousin
matching results that can be very helpful in specific cases. But
all so often I feel people take the ancestry.com autosomal report -
only later to wish they had taken a YDNA paternal line test (due
to their hope of proving common paternal ancestry with other Yanceys).
It just depends what your goals are and what your limitations are
(not all tests can be taken by everyone).
cautious of the phrase "DNA DOESNT LIE". Though I do agree that
genetic markers can be read with an extremely high degree of accuracy.
That doenst mean that DNA companies dont make the results seem like
it means one thing when it really doesnt. (especially in
the area of ethnicity and origin)
Give a single DNA report to 10 different people - and you'll probably get 10 different mis-assumptions or misperceptions.
And who is out there to rate the accuracy of DNA company test results ?? Not enough people . . ..