23andme tests the entire genome which is 22 chromosomes and
the X and the Y and mitoDNA.A male has one X and one Y.Everyone has
mitoChondrial DNA which they inherit from their mother, only females pass on
their mitochondrial DNA (mtDNA).Females have 2 Xs,one from each parent.Men get
one only from their mother..
The test is Autosomal which means across the whole genome
and arrayed are 2 of each chromosome ( maternal and paternal).They are in tiny tiny pieces called SNPS which is
different from older tests on
mitoDNA and Y DNA tests which are in STRS. STRS are bigger chunks of
DNA.
These autosomal snps are in clusters inherited through your
ancestors and are specific to YOU and your family.Anyone who you share a
segment with is related to YOU, the larger the segment the more closely
related.Smaller segments of less than 6.5cM are thought to indicate an
ancestral place or a very distant ancestor and shared by many more people.
I now have 1082 cousin matches,some are my first cousins who
I knew about. Others are startlingly with people I never knew about who descend
with me from John Carrow’s line
1660-1750; Charles Swanson in 1809;my many Irish ancestors and a few
cousin from the same small village north of the Arctic Circle where my
grandfather Sigurd Boe was born.
23andme also tests health traits for the same $99 and they
are also available to you without charge. Every time new tests get completed
new cousin matches and health traits are sent to you.
I have tested Family Tree DNA's Family Finder, 23andme and
DeCodeME ( by upload). I have not tested at AncestryDNA but it is available to
me via a cousin and it is not as good as the other two.
I feel 23andme is the BEST autosomal test It has the largest
database at about 200,000 and are now in a growth phase to reach 1 Million..
Family Tree DNA has about 35,000 and AncestryDNA has slightly more than 50,000
( they have given many free tests out)I am an Administrator of 5 surname groups at Family Tree
DNA, 3 Ancestor Projects at GEDmatch.comand 5 at Ancestry.com.
Gedmatch.com and others are called “third party” comparison
sites. They are available to folks for free.You must have access to your Raw Genome to transfer your
data to the third party sites.Ancestry.com currently does not allow you access
to your own genome so transfers cannot happen.
Family Tree DNA allows upload of 23andme genome for a
transfer fee of $89. You must have a V3( newer test) to do that upload.23andme
does not upload FTDNA data at this time. AncestryDNA used to allow you to manually
put your test results from other companies into their groups but that is no
longer being done.
DEcodeME is an Icelandic company that allowed genome
transfer but they have been purchased by another company.