What is a 3rd great-aunt or 3rd great-uncle?
Short answerYour 3rd great-aunt or uncle is a sibling of your 2nd great-grandparent. You are their 3rd great-niece or nephew: the 2nd great-grandchild of their sibling. You share 3rd great-grandparents, and a full 3rd great-aunt or uncle shares about 3.12% of your DNA on average.
The family line, drawn out
Follow the highlighted line from you up to the shared ancestor and down to them.
How to work it out
Go up 5 generations from you to a shared 3rd great-grandparent, then 1 down to their child. That child is a sibling of your 2nd great-grandparent, which makes them your 3rd great-aunt or uncle. Some genealogists write 2nd grandaunt or great-great-grandaunt instead; all name the same person.
Their spouse or partner is your 3rd great-aunt or uncle by marriage. Their children are your first cousin 3 times removeds.
What to call each other
| Them, to you | You, to them | |
|---|---|---|
| Female | 3rd great-aunt | 3rd great-niece |
| Male | 3rd great-uncle | 3rd great-nephew |
| Anyone | 3rd great-aunt or uncle | 3rd great-niece or nephew |
Their family and yours
Relationships shift by one step for each generation. Here is how the people around them relate to you:
| Their child | first cousin 3 times removed |
| Their parent on the shared line | 3rd great-grandparent |
| Your child sees them as your child’s | 4th great-aunt or uncle |
| Your parent sees them as your parent’s | 2nd great-aunt or uncle |
| What they call you | 3rd great-niece or nephew |
Shared DNA
On average, full 3rd great-aunts and uncles share about 3.12% of their DNA. That figure is the expected value: it halves with every generation of separation, and real amounts vary from person to person. A half relationship (through only one shared ancestor instead of a couple) shares about half as much: 1.56%.
Let Family Trees name it for you
In Family Trees, open anyone’s page to see how they are related to you in plain words, or choose any two people under How are they related?. The app counts the shortest blood line through birth and adoptive parents, names step, foster and in-law relations too, and uses exactly the words on this page. It’s free for a family of up to 100 people. You can also try the relationship calculator here.
Questions
What is a 3rd great-aunt or uncle?
Your 3rd great-aunt or uncle is a sibling of your 2nd great-grandparent. You are their 3rd great-niece or nephew: the 2nd great-grandchild of their sibling.
How much DNA do you share with a 3rd great-aunt or uncle?
About 3.12% on average. Each generation of separation halves the expected amount, and individual results vary.
What is my 3rd great-aunt or uncle’s child to me?
Your first cousin 3 times removed.