half siblings

[similligan]

Someone asked me if Family Finder would help determine if her sister was a full or half sibling. Under the old FF display, both the range and suggested relationship was displayed. Now all I see is the range. Will it be obvious which relationship is the correct one?

Thanks,
Susan

[mkdexter]

Susan:

It will be evident by the range.

Full siblings will show a relationship range of:
Parent/Child, Full Siblings

Half siblings will show a relationship range of:
Half Siblings, Grandparent/ Grandchild, Aunt/ Uncle, Niece/ Nephew

Matt.

[prairielad]

I believe they cut out the suggested relationship, the relationship range is still there.
following is a link to relationship ranges displayed.

http://www.familytreedna.com/faq/answers.aspx?id=17#826

A half sibling may fall into the 1 of 3 ranges, 2 of which also include Full Siblings. So it may not show a definite answer to whether a half sibling, but either ydna or mtdna will answer that question if further testing is needed.
test ydna if suspect different fathers
test mtdna if suspect different mothers.

I attached what is listed for my Father, his 2 siblings and their 1st cousin.

[prairielad]

..... either ydna or mtdna will answer that question if further testing is needed.
test ydna if suspect different fathers
test mtdna if suspect different mothers.

...........

Realized after responding my bolded comment will not apply since it deals with sisters, only mtDNA would be an additional option if suspect different mothers.

If suspect different fathers, testing a paternal 1st cousin and maternal 1st cousin will also help determine, if relationship range falls into the categories of Full Siblings, Half Siblings, Grandparent/Grandchild or Full Siblings, Half Siblings, Grandparent/Grandchild, Aunt/Uncle, Niece/Nephew

[1_mke]

Another option is uploading to gedmatch and doing a one to one comparison between the two. Full siblings should have a fair number of full base pair matches. If all or the vast majority of the matches are half base pair then you can pretty much be certain they are half siblings.

[similligan]

Thanks everyone!

[Wojciechowski]

Another option is uploading to gedmatch and doing a one to one comparison between the two. Full siblings should have a fair number of full base pair matches. If all or the vast majority of the matches are half base pair then you can pretty much be certain they are half siblings.

Thank you! This is a great idea.

Thanks to the original poster too. I really appreciate this thread as I am trying to answer this question for my mother's sisters as well.

[prairielad]

Another option is uploading to gedmatch and doing a one to one comparison between the two. Full siblings should have a fair number of full base pair matches. If all or the vast majority of the matches are half base pair then you can pretty much be certain they are half siblings.

This is actually the easiest and cost effective way if you are assigned the Full sibling/Half sibling range. By comparing kits one to one at Gedmatch it will either show you to have blocks of Full base Pair matches(Green) or just blocks of Half Pair matches (Yellow). Full pair would mean share maternal and paternal, while Half Pair would mean you only share either maternal or paternal side.

[keithet58]

Gedmatch?

For a novice like myself, were is gedmatch and how do I upload to it. I have been approached by a family that may be my half cousins, the same grandfather. I have done the GENO 2.0 DNA test and I have been able to surmise that I can somehow use this test to find family members? Do I have to redue DNA tests? or do I pay a reduced fee so they can re-look at my first DNA samples for different markers? Should I wait until my GENO 2.0 is complete it stands at 40 % complete?

[sleepy]

I'm glad I read this thread! I was unaware that the suggested relationship has been removed and you only get relationship range and in the case of siblings there is a relationship range that is both half and full siblings.


My brother and I just recently tested to try and figure out whether we are half or full siblings and have yet to get the results back. This info here is good to know in case we are assigned a relationship range here that is not clear whether we are half or full.

[teyoung]

The suggested relationship is still in the matches download.

[mkdexter]

suggested relationships are removed when a confirmed relationship is assigned. To see the suggested, just remove the confirmed one and it will revert back.

[emyr]

I have a new dilemma related to full/half siblings. Thought I would add to this thread rather than starting a new one.

I have tested two siblings, A (male) and B (female). Their shared cM is 2168.07. I have seen 2500 cM as the minimum shared value for full siblings, but not sure if this is set in stone. I've also tested a paternal first cousin. Sibling A only shares 300 cM with this first cousin, while sibling B shares 704.15 cM with the first cousin.

I also have a ydna test for sibling A and he does not match a paternal 3rd cousin who has also tested ydna (same surname and should be same direct male line so they should match).

More confusing is that sibling A is the eldest and was born in Austria to a US soldier and a Hungarian refugee. His parents married after his birth and brought him back to the US. Sibling B was born in the US to the same parents (US soldier from Mississippi and Hungarian mother).

I only see two possibilities:

1. Sibling A just simply inherited less autosomal dna from his father than from his mother (and the paternal 3rd cousin has an NPE in his line)

2. Sibling A has a different father than sibling B but this unknown father must be related to sibling B's father. This would mean that a cousin of Sibling B's father would have had to be in Austria at the time of Sibling A's conception.

Can anyone offer any guidance? I just recieved sibling B's results and will upload to gedmatch as soon as possible.

[msc_44]

those are half siblings numbers


700cm is right for a 1st cousin

300cm is right for a 2nd cousin

I have a new dilemma related to full/half siblings. Thought I would add to this thread rather than starting a new one.

I have tested two siblings, A (male) and B (female). Their shared cM is 2168.07. I have seen 2500 cM as the minimum shared value for full siblings, but not sure if this is set in stone. I've also tested a paternal first cousin. Sibling A only shares 300 cM with this first cousin, while sibling B shares 704.15 cM with the first cousin.

I also have a ydna test for sibling A and he does not match a paternal 3rd cousin who has also tested ydna (same surname and should be same direct male line so they should match).

More confusing is that sibling A is the eldest and was born in Austria to a US soldier and a Hungarian refugee. His parents married after his birth and brought him back to the US. Sibling B was born in the US to the same parents (US soldier from Mississippi and Hungarian mother).

I only see two possibilities:

1. Sibling A just simply inherited less autosomal dna from his father than from his mother (and the paternal 3rd cousin has an NPE in his line)

2. Sibling A has a different father than sibling B but this unknown father must be related to sibling B's father. This would mean that a cousin of Sibling B's father would have had to be in Austria at the time of Sibling A's conception.

Can anyone offer any guidance? I just recieved sibling B's results and will upload to gedmatch as soon as possible.

[S9 H9]

1. Sibling A just simply inherited less autosomal dna from his father than from his mother (and the paternal 3rd cousin has an NPE in his line)

Hmmm, not sure what this means. We all inherit 23 chromosomes from each parent, so no one gets "less". What is possible is that siblings just end up sharing little DNA because of the luck of the draw, in assorting the chromatids into gametes.

2. Sibling A has a different father than sibling B but this unknown father must be related to sibling B's father. This would mean that a cousin of Sibling B's father would have had to be in Austria at the time of Sibling A's conception.

It would not be the first time a woman bore children by brothers.

Can anyone offer any guidance? I just recieved sibling B's results and will upload to gedmatch as soon as possible.

Because inheritance is a random process the way to describe the results is with a probability distribution. The problem being, for those wanting a solid answer to questions like this, is that there is a non-zero, even if small, probability that two full siblings just don't inherit much of the same parts of their parents' chromosomes.

You're right about the possible NPE - it could have happened anywhere, starting with the common 2nd great grandparents.

It appears as if neither parent is available for testing, correct?