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cvolt
10-16-2016, 03:27 PM
I'm still new to comparing cM's and segments to my own. What do these two comparisons tell me? How much could they be related to me? Thanks!

Largest segment = 9.5 cM
Total of segments > 7 cM = 9.5 cM
1 matching segments
Estimated number of generations to MRCA = 5.7

and

Largest segment = 10.0 cM
Total of segments > 7 cM = 10.0 cM
1 matching segments
Estimated number of generations to MRCA = 5.2

MitchellSince1893
10-16-2016, 04:22 PM
I'm still new to comparing cM's and segments to my own. What do these two comparisons tell me? How much could they be related to me? Thanks!

Largest segment = 9.5 cM
Total of segments > 7 cM = 9.5 cM
1 matching segments
Estimated number of generations to MRCA = 5.7

and

Largest segment = 10.0 cM
Total of segments > 7 cM = 10.0 cM
1 matching segments
Estimated number of generations to MRCA = 5.2

Before you spend a lot of time on them, do you have relatives that also match these segments? I say this because at 9.5 and 10.0 cM there still is a statistically significant chance these matches are IBS rather than IBD...in other words false positives. According to one study just over 30% of 10 cM matches and 47% of 9 cm matches disappear after phasing.
False positive matches are more likely to be seen in unphased data (phasing is the process of assigning alleles to the mother or the father.) The highest degree of accuracy is achieved by using the phased data from a two-parent/one child trio, where the error rate for phasing is only 0.01%. http://isogg.org/wiki/Identical_by_descent#False_positive_matches

If they are indeed positive then what the above means is in the top example is your largest segment shared is 9.5 centimorgans. This is the only segment you share that is greater than 7 cM. It is estimated that the most recent common ancestor for you and the match lived 5.7 generations ago.
For what it's worth the estimated number of generations is usually too optimistic.
For genuine smaller shared segments in the range of 5 cMs to 10 cMs the common ancestor may be as many as 10 to 15 generations or more back in time. http://isogg.org/wiki/Identical_by_descent#False_positive_matches

cvolt
10-16-2016, 04:29 PM
Before you spend a lot of time on them, do you have relatives that also match these segments? I say this because at 9.5 and 10.0 cM there still is a statistically significant chance these matches are IBS rather than IBD...in other words false positives. According to one study 30% of 10 cM matches and 47% of 9 cm matches disappear after phasing.
False positive matches are more likely to be seen in unphased data (phasing is the process of assigning alleles to the mother or the father.) The highest degree of accuracy is achieved by using the phased data from a two-parent/one child trio, where the error rate for phasing is only 0.01%.
http://isogg.org/wiki/Identical_by_d...sitive_matches

If they are indeed positive then what the above means is in the top example is your largest segment shared is 9.5 centimorgans. This is the only segment you share that is greater than 7 cM. It is estimated that the most recent common ancestor for you and the match lived 5.7 generations ago.
For what it's worth the estimated number of generations is usually too optimistic.
For genuine smaller shared segments in the range of 5 cMs to 10 cMs the common ancestor may be as many as 10 to 15 generations or more back in time.
http://isogg.org/wiki/Identical_by_d...sitive_matches

Thanks! Unfortunately, I'm the only one in my family who has aDNA tested. It's less about the exact match, and more about the location the match is from. The first is Russian and it's one of several other Russian matches I have. All of them around the time that I would suspect a Russian (or similar) relative. The second one is Latvian. I suppose the only way to know for sure would be to contact them to find the common relative if there is one.