I just received my AncestryDNA results. It shows I have a close family match with a woman who would be my grandmother, aunt, or half-sibling. We matched 1,697cM with 51 shared segments.

It cannot be a grandmother.

Through our shared matches, I was able to determine that the common denominator for the shared matches was my father's mother's mother. She gave birth to a daughter who gave birth to my father, my aunt, and a half brother. All of them are deceased and have been for years -- they did not do DNA testing.

My aunt did not have children (they wouldn't test at 1700 anyhow, correct?) and the half brother who had children wouldn't test at nearly 1700 either and none of them showed up as matches (they are in my family tree).

I am a 47 yr old female. My grandmother died before I was born so we can rule out a grandmother.

Am I missing any other options here?

This looks to be a half-sibling, correct?


1 Answer 1


You can't assume anything. You've ruled out that this woman is your biological grandmother because your paternal grandmother died before you were born. But DNA is harsh. Sometimes your real family members are not your biological family. If your match is at least 70-75 years old, she could be your grandmother. If she is at least 13-15 years younger than any of your children (if you have children), you could be her grandmother.

Half-sibling is a strong fit based on the cMs and would mean that your dad fathered a child with a woman other than your mother. Depending on your match's age, she could have been born long before your mother came around. Your dad might not even had known about her. Or maybe he was married before and you didn't know.

But here's the thing, you say you have other matches and have used them to narrow down the family line your new match comes from. That you know she matches you on your "father's mother's mother's" line. If she were your half-sibling, she would match your close family matches on your father's father's line. And your father's mother's father's line. If she does not, then you are not talking about a half-sibling. But if she merely matches one or more people on that one great grandmother's line and you don't have people from other lines to look at, then you haven't ruled out half-sibling.

Given the fact that you have other matches and so can trace some family lines, and given the cM total of 1,697, with the Shared cM Project, here are your full set of options:

  • Grandmother/granddaughter. Not likely but not impossible if the age fits.
  • Half-sibling. Likely or impossible based on which other close family members of yours have tested and if they do or don't match with her.
  • Aunt/niece. Your father has a full sibling you didn't know about. (In this case the match would match close family from both your dad's mom's side and your dad's dad's side.)
  • Great aunt/niece. Your paternal grandmother has a full sibling you didn't know about.

You are correct to rule out your aunt's potential children (your first cousin) and your half uncle's children (half first cousin).

  • Hi there, thanks for your answer. I was on Shared cM Project & saw the 4 options which is why I am posting. I spoke with AncestryDNA. They suggested I go through the shared matches with this person & click on the common surname icon. DNA match and I have about 65 shared matches. The ones I checked list my Paternal GGM as the common surname. Recognized a 4th cousin, that's it. Was told that the common surname narrows it to my paternal GGM (Dad's GM). My paternal GF isn't the common thread, it's the paternal GM side. Not a GM/GD (age) or GA/GN match (out of match range). Leaves HS or A/N.
    – user8999
    Feb 15, 2019 at 8:21
  • One more quick question....of the shared matches between suspected HS/AN, the closest match is a definitive female 2nd cousin (no 1st cousin matches), the rest fall in the 4-6th cousin range. Will try to get my brother to test since my dad & aunt are gone & my grandparents on that side were also gone before I was born in 1971. This shared match didn't post a tree or give an age - there is no information - just looks like a first initial and last name. 2nd cousin match gives a full name but only 2 people in her tree. I do not recognize any names but the last name of 1 distant cousin - thoughts?
    – user8999
    Feb 15, 2019 at 8:43
  • @user8999 Yeah, this changes things. Do not rule out relationships based on other matches sharing a surname. You might be able to point to lines based on a very unusual surname, but never for a common one. Nor does the lack of a surname match rule out other distant cousin lines. Not everyone knows or lists all their surnames. You must talk to the match as your next step. Good luck.
    – Cyn
    Feb 15, 2019 at 15:36
  • 2
    She actually contacted me last night -- half-sister. Adopted when my father was 19. Thanks for all of your insight. I appreciate it.
    – user8999
    Feb 18, 2019 at 17:39
  • @user8999 Congratulations! I wish both of your families the best.
    – Cyn
    Feb 18, 2019 at 17:47

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