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Half or full siblings?

Half or full siblings?

Posted: 16 Jan 2015 9:30PM GMT
Classification: Query
Edited: 16 Jan 2015 9:37PM GMT
My husband Tim was adopted. After him taking the ancestry dna test and through a lot of research and help from his matches we thought we had found his birth family. His adoption records are closed but we were told all non identifying information they could give us. Who we found as his birth parents are both deceased but we did find their 2 children. The information matched. And there are some really amazing family resemblances. And through all of his dna matches on ancestry this lady was definitely Tim's mother. These 2 siblings we found have been thrilled! They were positive from family stories and matching information that they all 3 had the same mother and father. They did take the dna test also so we would have definite confirmation. We got their results back and we are having questions now as to whether or not they have the same father as Tim. On ancestrydna it is showing these 2 siblings as close family to Tim instead of immediate family. I did upload the raw data to gedmatch but I'm new to the dna stuff and don't understand it. Their kits have not finished batch processing but I was able to do a one to one comparison with the 3 of them.

Tim's one to one comparison with sibling #1(female) shows largest segment of 73.8 cm. Total of segments of 1713.9 cm. Estimated number of generations to MRCA is 1.5.

His comparison to sibling #2(male) shows largest to be 110.0 cm with total segments of 1869.1 cm and estimated number of generations to MRCA is 1.5

Sibling #1 and Sibling #2 comparison shows largest segment of 128.7 cm and total segments of 2555.5 cm with MRCA of 1.2.

Would we be correct in thinking that Tim is a 1/2 sibling to these 2 and that he has a different father? He has too many matches on the mothers side of the family for her not to be his mother.

Any help is much appreciated!!

Re: Half or full siblings?

Posted: 16 Jan 2015 9:36PM GMT
Classification: Query
I also did the X-dna comparisons with Tim and these 2 siblings.

Tim and female sibling#1 showed largest segment of 62.3 cm and total segments of 109.0 cm
Tim and male sibling#2 showed largest segment of 35.5 cm and total segments of 90.7 cm
Sibling#1 and Sibling2showed largest segment of 24.3 cm and total segments of 46.3 cm.

Re: Half or full siblings?

Posted: 17 Jan 2015 1:18PM GMT
Classification: Query
Full siblings will show some segments at GEDMatch color coded green for completely identical regions (roughly 25% of the genome).

Re: Half or full siblings?

Posted: 20 Apr 2015 2:29PM GMT
Classification: Query
Half siblings definitely.

Re: Half or full siblings?

Posted: 23 Jun 2015 3:58PM GMT
Classification: Query
Not necessarily half. Remember that each child gets 1/2 their DNA from each parent, however it is not the exact same half. If one is a male they could take a y-dna test at FTDNA. This would verify the males parental line.

Re: Half or full siblings?

Posted: 25 Jun 2015 1:10PM GMT
Classification: Query
Ok, so BY FAR the most likely thing is they're half siblings.

The average matching segments for half siblings is 1700. Full siblings are 2550. Parent/child is 3400. Double first cousins are 1593.75. First cousins are 850. Sure, you can get some deviation but why suspect aberrant deviation when the likelihood is half sibling?

I stand by half siblings.

Re: Half or full siblings?

Posted: 25 Jun 2015 3:15PM GMT
Classification: Query
my 1/2 sibling and I Share 1800-1900 cm autosomal total if that helps. We also share the same exact x chromosome because we are two females that share same father and different mothers.
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