Whose DNA do I have?

Dennis · Post by **Dennis** » Sun Mar 22, 2009 10:01 pm

Hi,

I got my x from my mom and my y from my dad, simple so far.
My mom got her xx from her dad and her mom. Whose x did I get,
her dad's or her mom's?

It just has me wondering what my maternal line is, my granny's or
my grandad's.

dennis

LesleyB · Post by **LesleyB** » Sun Mar 22, 2009 10:11 pm

Hi Dennis
there are lots of web sites which explain this - the X thing is a lottery as far as I remember and explains why two people can be siblings but completely different in looks attitude etc.

Best wishes
Lesley

Post by **SarahND** » Sun Mar 22, 2009 10:19 pm

Hi Dennis,
Interesting question! If I'm understanding it correctly, which is a big "if", then I think the answer is that it is comes from your mother's mother's mother's mother etc. At least this is the mitochondrial dna, which may not be what you're talking about

However, I learned something interesting from Wikipedia just now. "...mitochondria are normally inherited exclusively from the mother. The mitochondria in mammalian sperm are usually destroyed by the egg cell after fertilization. Also, most mitochondria are present at the base of the sperm's tail, which is used for propelling the sperm cells. Sometimes the tail is lost during fertilization. In 1999 it was reported that paternal sperm mitochondria (containing mtDNA) are marked with ubiquitin to select them for later destruction inside the embryo." So... although your father has his mitochondria from his mother, they are automatically destroyed after fertilization and you just get your mother's. Is that cool or what?

Regards,
Sarah

Dennis · Post by **Dennis** » Sun Mar 22, 2009 10:21 pm

Hi Lesley & Sarah

So I've possibly been wasting years on my family tree and a fortune on SP rummaging for my maternal line thinking it would link me to both my mom's paternal and maternal line.

dennis

LesleyB · Post by **LesleyB** » Sun Mar 22, 2009 10:51 pm

Hi Dennis
I cannot find the web site which explained it all with helpful images, as I am not working on my own PC just now, where the bookmarked web site is, but this perhaps explains what I was trying to say:

http://www.thednaclinic.co.uk/srvc_sibling.html

However, Siblings do not have the exact same DNA, as the inheritance of alleles from biological parents is random. At each genetic location (part of the DNA) a person possesses two alleles. A person will only pass one of these alleles to their offspring. Which allele is completely random. Therefore one child could inherit one allele from his father, while the child’s brother or sister could inherit the other. The allele inherited from the father joins with the allele inherited from the mother for that genetic location, when an egg is fertilized by a sperm. This is duplicated millions of times along the DNA molecule to form a child’s own unique DNA, made from half its fathers and half its mothers DNA.

Best wishes
Lesley

LesleyB · Post by **LesleyB** » Sun Mar 22, 2009 11:10 pm

Also:

Each person normally has one pair of sex chromosomes in each cell. Females have two X chromosomes, while males have one X and one Y chromosome. Both males and females retain one of their mother's X chromosomes, and females retain their second X chromosome from their father. Since the father retains his X chromosome from his mother, a human female has one X chromosome from her paternal grandmother, and one X chromosome from her mother.

http://en.wikipedia.org/wiki/X_chromosome

Dennis · Post by **Dennis** » Sun Mar 22, 2009 11:32 pm

Hi/sigh

So on my mom's side I come from a long line of mothers and cannot claim, genetically, to be descended from her dad

dennis

LesleyB · Post by **LesleyB** » Sun Mar 22, 2009 11:52 pm

Hi Dennis
I'm no scientist, and I'm sure someone more qualified would make a better job of this, but I think you have it pretty well summed up there!

But hey, look on the bright side - your Y DNA (male line) should have been passed on all the way back to the year dot!!

http://www.familytreedna.com/inheritance-chart.aspx
http://www.dnaheritage.com/ystr.asp

http://www.cellmark.co.uk/dna_testing/y ... esting.php

DNA is organised into 46 chromosomes, 23 inherited from their mother and 23 inherited from their father. One chromosome, called the Y-chromosome, is only present in men and is transmitted from a father to his son unchanged.

Genealogy: The Y-chromosome test can be used to provide evidence linking individuals to a common male line as they share the same Y-STR profile, or it can provide proof that they are not related. This type of test is often used in surname projects which involve large groups of individuals with a common surname who are interested in researching their ancestors.

Best wishes
Lesley

Post by **SarahND** » Mon Mar 23, 2009 12:03 am

LesleyB wrote: But hey, look on the bright side - your Y DNA (male line) should have been passed on all the way back to the year dot!!

And, as far as I can tell, we females have no genetic connection to the people with our maiden surname

I have 4 family files in my genealogy program, one for each grandparent. In trying to make a list of all the relatives going back, taking the mother and paternal grandmother and then each one of their mothers and paternal grandmothers-- leapfrogging always the maiden surname... I quickly realized that I wasn't using one of my four files at all. It only applies to my brother and his children

Must say, I never thought of it this way before. I'm finding all sorts of lines that should be followed back! All the hard ones...

Regards,
Sarah

LesleyB · Post by **LesleyB** » Mon Mar 23, 2009 12:36 am

Hi Sarah

I'm finding all sorts of lines that should be followed back! All the hard ones...

Aye, well, as Tammy once said..."Sometimes it's hard to be a woman..."

but I don't think she'd DNA in mind at the time.

Best wishes
Lesley