3rd cousin twice removed, etc.

So what determines degree of relation and removal? Is a 3rd cousin once removed closer than a 2nd cousin twice removed? And does it only apply to cousins?

“Removed” refers to generations. Quoth Wiki:

The degree (first, second, third cousin, etc.) indicates one less than the minimum number of generations between both cousins and the nearest common ancestor. <snip> The removal (once removed, twice removed, etc.) indicates the number of generations, if any, separating the two cousins from each other.

A good visual (as opposed to text) answer is here.

1st, 2nd. 3rd cousins have to do with nearest shared ancestors: first cousins share a grandparent, second cousins a great grandparent, 3rd cousins a great-great grandparent.
“Removes” are generational offsets: my first cousin’s children are my first cousins, once removed. Their children will be my first cousins, twice removed. My children and my first cousins-once-removed will be second cousins to each other, because their nearest shared ancestors are their great-grandparents (mine and their parent’s grandparents)

Also: http://www.straightdope.com/columns/read/516/whats-the-term-for-your-cousins-children

Well, define “closer”. You mean least number of generations to the common ancestor?

That means siblings score 2, if we accept the convention that we count person A’s distance from the ancestor and add person B’s distance, i.e. a score of “1” means the ancestor is a parent, “2” means a grandparent, etc. “Removed” means find the closest possible cousin parity (i.e. whichever cousin is closer to the ancestor) and adding for each generation.

First cousins would score a 4. First cousins once removed would be a 5 (one cousin scores a 2, the other’s *parent * would also score a 2, giving the second cousin a score of 3). First cousins twice removed score a 6. Second cousins would also be a 6. Second cousin twice removed is an 8. Third cousins would also score 8. Third cousins once removed would be a 9.

Huh. I also thought “removed” meant how many times they’d been blacklisted from the family only to regain their position again. Learn something new every day.

So for an example, how would these be termed in relation to me. My mom’s first cousin? His kids?

Your mom’s first cousin is your first cousin, once removed.

His kids are your second cousins.

No idea if you’re being serious, but I genuinely assumed this to be the case until I was ten or eleven. When I read biographies of folks and came across these terms, I always found myself flabbergasted how common it (apparently) used to be for people to be disowned and then welcomed back.

When I found out the correct meaning, I was very :eek: :smack:

What I find interesting in that chart is there are TWO “first cousins, once removed,” TWO “first cousins, twice removed,” etc., yet the lineage is quite different. I can only assume that the amount of “removed-ness” is equivalent in spite of the significant differences.

Well that only happens because the two people are of different generations and are named for the lower number. A first cousin’s kid is your first cousin, once removed, because you have the higher number (your kids will be second cousins to that person). But if that person has a first cousin of their own, then that first cousin’s kid will also be a first-once.

In other words, if you’re 2nd generation from some ancestor, then you’re first-once with a person in the first generation (your mom’s cousin) where you’re junior, and you’re the elder to someone from the 3rd generation (your cousin’s kid).

It’s really no different that if instead of an uncle/nephew pair, we called both parties “uncle”. That is, instead of saying “He’s my uncle and I’m his nephew”, you’d say “We’re uncles to each other.” Then you’d be an uncle to your actual uncle, and any nephews you have would be uncles to you, too. So you’d have an older uncle and a younger uncle, (by generation of course, not age).

Not really. The relationship of the “first cousin once removed” to the immediate lower right of “Self” (which I’ll call FCOR1) to “Self” is the same as the relationship of “Self” to the other “first cousin once removed.” (i.e. FCOR2)

FCOR1’s grandparent (“uncle/aunt”) has a sibling (“mother”) who is parent to “self”.

Self’s grandparent (“grandmother”) has a sibling (“great-uncle/aunt”) whio is parent to FCOR2.

As my mother used to say, the ordinal numbers matter if you want to get married, the removes matter if you think you’re going to get an organ off of them.


Simplest way to put it: Nth cousins share a common ancestor in the same generatio0n of descent from him. (Note that this is measuring generations of descent – it’s entirely possible after a few generations to have Nth cousins dozens of years different in age. Take one of the old large families,where young people would marry at 18 and have their first child young, and continue having children for a decade or two. A firstborn son of a firstborn son of a firstborn son might be 40 years older than his second cousin, who was the 10th child of a 12th child of a 14th child.)

Siblings, which could be conceived of as “zeroth cousins”, share a set of parents. First cousins share a set of grandparents. Second cousins share a set of great-grandparents. And so on.

Removals show relationship between relatives of different generations of descent. Your and your father’s first cousin are first cousins, once removed, as are you of your own first cousin’s child. Your grandfather’s cousin is your first cousin twice removed; so is your first cousin’s grandchild. The same holds true for second cousins, and so on.

An uncle responded to me once when I asked how come no one called cousin <name> my first cousin once removed?

He said, “In our family, we don’t remove em, we just quit talking to em.”

I have always remembered that.


I first came across this (to me) weird system in Robert Heinlein’s book Citizen of the Galaxy and thought it was his invention for the specific setting of the book. Little did I know it existed in real life.

From the OP:

Yes, but that’s all it needs to apply to. Every blood relationship other than sibling, ancestor/descendant, or (aunt/uncle)/(niece/nephew) can be expressed as Xth cousin Y times removed. And of course we already have names for all of the combinations that aren’t called “cousin”. Of course, the terminology could be extended to those, too: I could refer to my sister as my zeroth cousin, or to my uncle as my brother once removed (or zeroth cousin once removed).

Number the generations sequentially, ascending from older generations to younger.
gen(x) is the generation number of person x.

Persons p1 and p2 are (Degree) cousins (Remove) removed where

Degree = min(gen(closest common ancestor)-gen(p1),gen(closest common ancestor)-gen(p2)) - 1
Remove = abs(gen(p1)-gen(p2))

You’re a hobbit, and a mathematician?


No, it isn’t. In all other situations, my relationship to you is not required to be the same as your relation to me. If I am your parent, you are my son or daughter. If I am your brother, you are either my brother or sister. If I am your nephew, you are my aunt or uncle. But, if I am your (any type of) cousin, then you are my (same type of) cousin.

It is weird. I honestly don’t understand why we don’t have a separate word. It seems odd to create a system to remove such ambiguity, and then leave such an obvious example.

BTW, is there any better term for my maternally maternal great-grandmother?