DNA Tests for Genealogy Purposes

Claudia, In the spirit of your post I wanted to share my DNA results based on the the X and Y chromosomes.

Paternal: Haplogroup I2a (P37.2)
Maternal (mtDNA): Haplogroup B

The maternal result isn't surprising as it's found among those that initially colonized the Americas over 10,000 years ago.

For me, the surprise is finding that my paternal DNA is P37.2, which is a predominant marker found among Balkan countries today. I've found two people with the same marker and last name (Gonzalez) as my father who are also from the same area in Zacatecas, Cuquio and La Villita near Jalpa. My father's ancestors (at least as back as ~1770) are from La Villita. I haven't yet made the genealogical connections with these two other lines, but it's great to know that there are a lot of undiscovered connections out there. Cuquio and Jalpa lie on the south-north road connecting Zacatecas and Guadalajara, and also are connected via Yahualica, Teocaltiche, Nochistlan, and Calvillo.
It's not clear how common P37.2 is among Mexicans. Does anyone else have this marker?

Arturo G

Claudia,
You stated that the substitution rate of the X-chromosome is fast, and the reason why X-chromosomes are not used to determine genealogies. I respectfully disagree. X-Chromosomes in mammals, including humans, display substitution rates slower than autosomes (non-sex chromosomes). Several hypotheses have been advanced to explain this slower rate, but purifying selection against deleterious mutations is perhaps the most plausible explanation. Thus a slow mutation rate is perhaps one reason why X-chromosomes are not used genealogical studies. I can think of other reasons, including the high potential of this metacentric chromosome for crossing-over during meiosis. This type of genetic recombination would produce genealogies that cannot be easily solved, as the new chromatid now includes mom's and dad's contribution.

Sincerely

Jaime Alvarado

Hello Claudia,

I haven't said anything that stated or inferred anything different. My
statement about mtDNA being passed down from mother to son may have been
interpreted incorrectly, I was only pointing out that men can test for
mtDNA. If there has been a misunderstanding about some of my posts please
let me know.

Now that you bring up Autosomal DNA. The following is directly from
FamilyTreeDNA -

** Due to the nature of autosomal DNA, the test does not specify from which
branch of your family tree your matches or the percentages of your
geographic heritage derive.

Therefore, you cannot get one's complete ethnic origin breakdown from an
AUTOSOMAL DNA analysis. A complete ethnic origin breakdown would actually be
impossible for almost everybody and this shouldn't be expected to be
acheived at all. No one has inferred that this can be done. I am curious as
to what led you to believe someone had inferred such is possible or is even
being attempted.

Armando

On Thu, Aug 4, 2011 at 7:34 PM, wrote:

> I think there is a lot of confusion here about DNA, how it's tested, and
> how to interpret our results. I hope that the below will clear up some
> confusions...
>
> There are four (4) types of DNA in humans that are used for molecular
> genealogy:
>
> 1) Autosomal DNA - inherited from both MOTHER & FATHER (we inherit 50% from
> mom/50% from dad)
>
> 2) X-chromosome DNA - determines gender; whether we are female (XX) or male
> (XY), females pass on their X chromosome to ALL children, fathers pass on
> their X chromosome to their DAUGHTERS only and their Y chromosomes to their
> SONS only. X-chromosome DNA changes rapidly from generation-to-generation,
> and so it is not very useful for deep ancestry research
>
> 3) Y-chromosome DNA - only men have this and because men only have 1
> Y-chromosome, it passes unchanged from FATHER-to-SON over many generations
> going back deep into one's ancestry on DIRECT male line
>
> 4) Mitochondrial DNA - both men and women have this, but only a MOTHER can
> pass it on to her SONS and DAUGHTERS; it passes from
> generation-to-generation unchanged for thousands of years (deep-deep
> ancestry on DIRECT female line)
>
> A man can be haplotype R1b (European), but still be 30% native-American,
> African, Asian, whatever. In this case, we only tested his Y-chromosome and
> results prove that his direct PATERNAL line has European origins. Now, if
> he tests his Mitochondrial DNA (mtDNA), he can also have a European result,
> but at the same time be 30% Native-American, African, Asian...whatever. We
> only tested his MATERNAL line
>
> In order to get one's complete ethnic origin breakdown, one needs to get an
> AUTOSOMAL DNA analysis. This test takes a different strand of human DNA
> (NOT related to yDNA or mtDNA), that is passed on randomly from BOTH mother
> and father to each child. We get 50% from mother and 50% from father. Our
> mother got 50% from her mother and 50% from her father...and our father got
> 50% from his father & 50% from his mother...etc, etc...all the way up our
> family tree. It is a complete genetic record.
>
> I think that as more and more NR members get tested, we will learn that we
> who descend from the founding families of Jalisco, Zacatecas &
> Aguascalientes are not 100% pure Spanish/Portuguese/Italian/**French . We
> are all a mixture of the three major ethnic groups who populated the region
> and who comprise our ancestry: European, Native American and African. This
> is being proven by DNA test results every day.
>
>