What is a second cousin?
A second cousin is someone who shares a set of great-grandparents with you, but not grandparents. In practice, they are the child of one of your parent's first cousins.
- Shared ancestor
- 3 generations up from you
- They call you
- their second cousin
- Average shared DNA
- ≈ 3.13%
- Cousin number · removed
- 2 · 0
How to spot a second cousin
Your parents have first cousins: the children of your grandparents' siblings. The children of those first cousins are your second cousins. You sit in the same generation, three steps below the great-grandparents you share.
A quick test: if your grandmother and their grandfather were sister and brother, you two are second cousins.
Second cousin vs first cousin once removed
This is the mix-up behind most searches. Your first cousin's child is not your second cousin; they are your first cousin once removed, because they sit one generation below you. Your children and your first cousin's children, however, are second cousins to each other.
How much DNA do second cousins share?
On average about 3.1% of their autosomal DNA, or roughly 230 centimorgans, according to the Shared cM Project run by genetic genealogist Blaine Bettinger. The real range is wide, from around 40 cM to over 500 cM, and a small share of second cousins can look like third cousins in a DNA test.
Check your own relative
Not sure this is the right term? Enter your actual connection.
Find the most recent ancestor you both descend from, then say how each of you is connected to them.
- They call you
- their second cousin
- Expected shared DNA
- ≈ 3.13%
- Degree (civil / canon)
- 6 / 3
- Also called
- 2nd cousin
Why a second cousin?
You share great-grandparents. You are 3 generations below them; the other person is 3 generations below them.
The cousin number comes from whoever is closer to the shared ancestor: 3 generations down, minus 1 = second cousin.
You are the same number of generations down, so there is no "removed".
Questions people ask
Are second cousins blood related?
Yes. Second cousins share a pair of great-grandparents, so they are blood relatives, although they share only a few percent of their DNA on average.
What is my second cousin's child to me?
Your second cousin once removed. They are one generation below you, and the "second" stays because you are the one closer to the shared great-grandparents.
What is my parent's second cousin to me?
Also your second cousin once removed, this time in the older generation. They share great-great-grandparents with you.
Can second cousins marry?
In the US, UK, Canada and most of the world, marriage between second cousins is legal everywhere. Restrictions, where they exist, apply to first cousins.