View Full Version : Percentage of DNA Shared and IBD Segments Question

J Man
09-25-2013, 11:29 PM
Hi All,

I was wondering if anyone here with a good knowledge of autosomal DNA inheritance patterns could answer a question for me? I am quite sure that my grandmother and her brother are full siblings and I think my match with him at 23andme may prove it. At 23andme on Relative Finder my great uncle and I share 14.5% of DNA in common and 35 segments. My question is then say if my grandmother and my great uncle here were half siblings would it even be possible for me to share this amount of DNA and that number of segments with him? Do these results pretty much prove that they were full siblings or not?

I see in the link below here that the average amount of DNA that a great uncle and great nephew share together is around 12.5%.


09-29-2013, 05:29 AM
This is a nice little illustration, of course keep in mind that the percentages shown are not as cut and dried in reality, which you already know.