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What is my grandma's sister's daughter to me?

Your grandma's sister's daughter is your first cousin once removed, and you are her first cousin once removed too.

6.25% shared DNA on average. Real amounts vary.

Diagram: how your grandmother's sister's daughter is related to youYouParentGrandmotherGreat-grandparentscommon ancestorsGreat-auntFirst cousin onceremovedthem

you them common ancestors double line: marriage

Your grandma's sister is your great-aunt; her daughter is your parent's first cousin. That makes her your first cousin once removed.

A quick check: you and she share your great-grandparents (her grandparents). You are 3 generations below them, she is 2. The smaller number minus one gives “first” cousin; the difference of one gives “once removed”.

How we worked it out

Follow the chain one step at a time:

  1. Your grandmother: grandmother (2 up, 0 down)
  2. Your grandmother's sister: great-aunt (3 up, 1 down)
  3. Your grandmother's sister's daughter: first cousin once removed (3 up, 2 down)

Your great-grandparents are her grandparents: they are your common ancestors.

She is one generation above you.

Count the generations to your common ancestors: 3 up from you, 2 down to her. The cousin number is one less than the smaller count (2), so first cousin. The counts differ by 1, so once removed.

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    Related questions

    Is my grandma's sister's daughter my aunt?
    Not technically. She's your parent's first cousin, which makes her your first cousin once removed. Families often call her “aunt” as a courtesy.
    What are my grandma's sister's grandchildren to me?
    Your second cousins. You share great-grandparents and are the same generation.

    More family relationship answers