With our experts Michelle Leonard, Shauna Hicks & David Frost
Is this a false-matching DNA segment?
Q I uploaded my AncestryDNA results to MyHeritage, but am having a few issues in trying to work out how some matches are related to me. For example, two of my matches are father and daughter, but I was puzzled to see that I share more cMs with the daughter than the father.
According to MyHeritage I share 75.5cM with the daughter and only 60.9cM with her father. The daughter shares two additional segments (13cM directly before a segment the father also shares and 7cM on a separate segment) while the father shares a solo 6.5cM segment.
Apart from the DNA shared with all three of us, the daughter shares two segments on Chromosome 1 with me, that her father doesn’t.
I don’t have any close relatives and (as my mother was an only child and none of my father’s siblings had any children) I don’t even have any first cousins! My closest Ancestry matches are two of my mother’s maternal first cousins. As my mother was born in 1927, I’m not expecting to find many more matches at this level in the future. On MyHeritage, my closest match shares 134 cMs with me (but I suspect that she is on my paternal line). Also having a number of unknown ancestor mysteries doesn’t help! I suspect the father and daughter matches (mentioned above) are related to me through my mother’s paternal line for whom I have fewer matches.
Sue Greenwood
3. The additional segments are false positives/pseudosegments and this is the most likely explanation for the anomaly.
If Sue had close maternal and paternal only matches with whom she shares the larger Chr 1 segment, that could help her with working out if it is a false segment. Since she doesn’t have such close relatives to test, I would recommend asking if the match has a close maternal relative tested instead.
If the daughter has a close maternal relative who shares the Chr 1 segment with her, and this person doesn’t match Sue on the segment, that would confirm it is false as it is not possible to share a segment that wasn’t inherited from one of her parents. I would also recommend that Sue adds her best matches to MyHeritage’s one-to-many chromosome browser in batches to try to find others who share the segments. If she can find matches sharing them on her maternal and paternal copies of Chr 1, she can compare with the daughter to work out if it is false as I suspect. ML
A There are only three options for why Sue shares more DNA with the dau
