What is a 2nd great-grandparent?
Short answerYour 2nd great-grandparent is your great-grandparent’s parent. You are their 2nd great-grandchild. A 2nd great-grandparent is a direct-line ancestor, 4 generations above you. You inherit about 6.25% of your DNA from each 2nd great-grandparent 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
Count the generations straight up: parent is 1, grandparent 2, great-grandparent 3. A 2nd great-grandparent is 4 up. From 2nd great-grandparent on, genealogists number the “greats” to keep them readable: a 3rd great-grandparent is a great-great-great-grandparent.
Everyone has 16 2nd great-grandparents by birth, 8 on each parent’s side, unless the same person appears twice in the tree (cousins who married, which genealogists call pedigree collapse). Family Trees always takes the shortest line, so someone who is both a grandparent and a great-grandparent reads as grandparent.
What to call each other
| Them, to you | You, to them | |
|---|---|---|
| Female | 2nd great-grandmother | 2nd great-granddaughter |
| Male | 2nd great-grandfather | 2nd great-grandson |
| Anyone | 2nd great-grandparent | 2nd great-grandchild |
Their family and yours
Relationships shift by one step for each generation. Here is how the people around them relate to you:
| Their other children (not on your line) | 2nd great-aunt or uncle |
| Your child sees them as your child’s | 3rd great-grandparent |
| Your parent sees them as your parent’s | great-grandparent |
| What they call you | 2nd great-grandchild |
Shared DNA
On average, you inherit about 6.25% of your DNA from a 2nd great-grandparent. That figure is the expected value: it halves with every generation of separation, and real amounts vary from person to person.
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 2nd great-grandparent?
Your 2nd great-grandparent is your great-grandparent’s parent. You are their 2nd great-grandchild.
How many 2nd great-grandparents do I have?
Everyone has 16 2nd great-grandparents by birth, 8 on each side, unless an ancestor appears twice because relatives married each other.
How much DNA do you share with a 2nd great-grandparent?
About 6.25% on average. Each generation of separation halves the expected amount, and individual results vary.
What is my 2nd great-grandparent’s child to me?
Your 2nd great-aunt or uncle, on the same line.