Autosomal sibling test?

[burto]

Hi,
I've just noticed that FTDNA do the 9 CODIS panel that can show siblingship. Looking at my Mum's and her half sister's they only match about 4 alleles where it's obvious that the others in the pairs are from their different fathers-there are 2 marker pairs that match exactly! The rest are all different.
Why do they match 2 marker pairs, just coincedence?
And why are the remaining marker pairs completely different?
E.g. Mum gets 10, 10 Aunt gets 9, 11.

[tomcat]

Hi,
I've just noticed that FTDNA do the 9 CODIS panel that can show siblingship. Looking at my Mum's and her half sister's they only match about 4 alleles where it's obvious that the others in the pairs are from their different fathers-there are 2 marker pairs that match exactly! The rest are all different.
Why do they match 2 marker pairs, just coincedence?
And why are the remaining marker pairs completely different?
E.g. Mum gets 10, 10 Aunt gets 9, 11.

In the example, the common mother might have been 9,10 with one father contributing a 10 and the other an 11. The shared marker pairs are also not out of the ordinary, for example the common mother might have been 8,8 with one father a 10,12 and the other a 12,12 in which the odds favor each half sister getting an 8,12.

But, you really don't have sufficient test results to make attibutions because each half-sister's results only contains half of her parents' alleles.

[burto]

I see so would X testing help to determine which X is shared and which isn't and can they be entered into a database to find possible relatives?

[tomcat]

I see so would X testing help to determine which X is shared and which isn't and can they be entered into a database to find possible relatives?

You might have better luck with X because you need only account for 3 alleles. A father has only 1 version of X which he got from his mother and is conserved in him because he has no other X with which it could recombine. Mothers, on the other hand, have 2 versions of X that can recombine in ovogenesis - hence the common mother of the half-sisters might have contributed a different version of an X to each daughter. Your best bet are the linked markers, 10074,75,79, that do not recombine but descend in a block. The GM had 2 and the fathers each contributed 1. If the half-sisters have a haploblock in common it is more likely the 1 on which they differ came from the respective fathers.

Open a free account at: www.dna-fingerprint.com
And post results in Xmatch.

[burto]

So which x panel should they order and will this haploblock definately be shared by both half sisters? If not then it's an expensive lottery. Is it still possible that they will differ depending on which haploblock they got from their mother's two? If that is the case then how do these sibling tests work as surely this could happen to every child born even from the same parents?
Many thanks.

[tomcat]

Haploblock may not be shared by both sisters. You buy your ticket and you take your chances. Results may still be posted at Xmatch and you might still find a lead. Are there any uncles available or other close relatives? I think the haploblock is on X STR Panel One.

[burto]

What about my Aunt's daughter? Or me? That's about it really...don't know Mum's Dad or his family and her Mum's family don't talk

[Kathleen Carrow]

Haploblock may not be shared by both sisters. You buy your ticket and you take your chances. Results may still be posted at Xmatch and you might still find a lead. Are there any uncles available or other close relatives? I think the haploblock is on X STR Panel One.

My Sister and I only shared the haploblock from our Dad (16,15,16)..so she got one haploblock ( 3 markers) and I got another three..

I am going to test my female cousin on Mom's side and see how that goes..

And if you already tested here at FTDNA you can just test those three markers..$8.68 or something like that per marker..
I tested my son's and he has mine..18,8,18
Sister's is 17,17,19..
I THINK that the DXS10067,10068,10069 is also supposed to be slightly informative..
I forget where I heard that tho'

[burto]

So if Mum buys the test, does that mean my Aunt and cousin would get it cheaper ir do they have to pay full price too?

[Kathleen Carrow]

So if Mum buys the test, does that mean my Aunt and cousin would get it cheaper ir do they have to pay full price too?

NO! it is only cheaper if your sample is already at Family Tree DNA..
I tested my one cousin and my Sister..so when I do my Sister's X Markers it is $8.68 per marker but of course it is not that cheap if your sample is not there..

Do you have any of your family who have their sample here? Who tested here? THEY would be cheaper if you tested their X markers..you do NOT have to test the whole Panel..

I will have to pay $110 to test my female cousin's panel..

In the meantime I am finishing up my sister's X markers..3-4 at a time..
her markers compared to mine will give me my Dad's entire profile..
which is my paternal grandmother's family..also mostly Irish..even tho' it is my Colonial America line also..

IF you tested your Mom and her sister..if they had a haploblock in common..the OTHER 3 markers of your Mom could be compared against a known relative of HER father..your biological grandfather( at least I think that is correct ).. is he known to you?
My biological Paternal GF is NOT known to me..

[tomcat]

What about my Aunt's daughter? Or me? That's about it really...don't know Mum's Dad or his family and her Mum's family don't talk

Always best to test as far back up the lines as possible! If you test descendants you are just adding more unknowns to the problem. Find and/or convince famly to test. The DNA of family elders is IRREPLACEABLE ... they may be flattered.

[tomcat]

...
I THINK that the DXS10067,10068,10069 is also supposed to be slightly informative..
I forget where I heard that tho'

There does seem to be a bit of pattern across 10067 and 10068.

For example if you enter 13 for 10067 you will find 4 with 22 at 10068. If you enter 14 at 10067 you will find 5 with 21 at 10068. If you enter 15 at 10067 you find a high incidence of 21 at 10068. And if you enter 16 at 10067 that 20 and 21 occur about equally at 10068.

I don't see these correspondences carrying over to 10066 or 10069.

[burto]

Always best to test as far back up the lines as possible! If you test descendants you are just adding more unknowns to the problem. Find and/or convince famly to test. The DNA of family elders is IRREPLACEABLE ... they may be flattered.

Hi,
My Gran died and she was an only child-that's why I wondered if getting my Aunts daughter tested might help as surely she would get the same X as her Mum and ultimately that would help us determine which X was from my Mum and Aunts mother?

[haplogroupc]

Isn't it true that the X test reveals the father's maternal line? In a situation like burto's mom and my mom who don't know anything about their fathers, could we get a clue about their father's ancestry that way? I know that my mom shares some X markers in common with someone else whose ancestor is from the same area as her father.

[tomcat]

Hi,
My Gran died and she was an only child-that's why I wondered if getting my Aunts daughter tested might help as surely she would get the same X as her Mum and ultimately that would help us determine which X was from my Mum and Aunts mother?

Your aunt's daughter's maternal X is a recombined product of your aunt's X's. All potential information about your aunt's maternal X is available in your aunt's X results. You add nothing by testing her daughter.