2nd Cousin 1x Removed: Exactly Who That Is, and What the DNA Says

A 2nd cousin 1x removed is either your parent's second cousin or your second cousin's child. Both directions carry that same label, and both share roughly 1.56% of their DNA with you on average, which lands somewhere around 120 centimorgans on a consumer test. The "1x removed" is shorthand for "once removed," and all it means is that the two of you sit one generation apart on the family tree.

This is the relationship that shows up constantly in DNA match lists and almost never in conversation. It is close enough to be reliably detected, distant enough that most people have no idea who the person is, and ambiguous enough that the centimorgan total alone will not confirm it.

What "1x Removed" Actually Means in 2nd Cousin 1x Removed

The "1x" counts generations between you, not degrees of closeness. It is not a measure of distance in the family, and it says nothing about how well you know each other.

You will see this relationship written several ways, all identical in meaning:

• 2nd cousin once removed
• 2nd cousin 1x removed
• 2C1R
• second cousin, once removed

The compressed forms come from genealogy software and DNA platforms, where full relationship names take too much room in a table. DNA Painter, the Shared cM Project, and most clustering tools use 2C1R. Ancestry spells it out. The various shorthand systems, including how half relationships and multiple removals get notated, are covered in abbreviation for cousin.

One thing the notation does not tell you is which direction the removal runs. 2C1R covers both the older-generation version and the younger-generation version with the same four characters. You have to work out from context whether the person is your parent's second cousin or your second cousin's kid.

Who a 2nd Cousin 1x Removed Actually Is

There are exactly two ways to be a 2nd cousin 1x removed to someone, and they are mirror images.

Direction one, the generation above you. Your parent's second cousin. Your mother or father and that person share great-grandparents. Because you are one generation below your parent, you are one generation removed from their second cousin.

Direction two, the generation below you. Your second cousin's child. You and their parent share great-grandparents. Their child is one generation below you.

Both are 2C1R. The relationship is fully reciprocal, so if someone is your second cousin once removed, you are theirs, with no senior or junior version of the term.

The rule that produces all of these is short. The cousin number comes from the closer person's distance to the shared ancestor, minus one. The removal count is the difference between the two people's distances. Feed two people into the free calculator at cousinchart.com and it runs both numbers for you.

The Common Ancestor

The shared ancestors are the older person's great-grandparents, which are the younger person's 2x-great-grandparents.

Take direction one. Your parent and their second cousin both descend from a couple three generations above them: their great-grandparents. Those same people are four generations above you, making them your great-great-grandparents. So one couple sits at the top, three generations down to one cousin and four generations down to the other.

Run the arithmetic to check it. The closer person is 3 generations below the ancestors, so 3 minus 1 gives cousin degree 2. The difference between 4 and 3 is 1, giving one removal. Second cousin once removed, confirmed.

That common ancestor couple was likely born in the mid-to-late 1800s or early 1900s for most people alive now, which is comfortably inside census, immigration, and vital-records territory. Unlike the vanishing paper trail at 5th cousin, a 2C1R connection is usually documentable if you are willing to spend an afternoon on it.

Age Tells You Nothing

A 2nd cousin 1x removed can be older than you, younger than you, or exactly your age. Removal counts generations, never years.

Families run at wildly different speeds. If one branch had children at twenty and another at forty, three generations of that difference stacks up to sixty years of drift. It is entirely ordinary for a person's second cousin once removed in the older generation to be younger than they are, and for the one in the younger generation to be older.

So never use age as a shortcut to identify one of these matches. Two people born the same year can sit a generation apart on the tree, and two people fifty years apart can be the same generation. Only the path to the common ancestor decides the label. The same trap catches people trying to sort out what is your mother's cousin to you, where a "cousin" a generation up often turns out to be a teenager.

The DNA Numbers

Second cousins once removed share about 1.56% of their DNA on average, roughly 106 to 122 centimorgans depending on which source you use. The observed range in real testers runs from about 14 cM to about 350 cM.

Those two numbers, an average and a range, do different jobs, and using the average alone will lead you astray.

The theoretical expectation. Each step out halves the expected sharing. Second cousins average 3.125%. Adding one removal halves it to 1.5625%. Against a total autosomal genome of roughly 6,800 cM, that predicts about 106 cM.

The observed average. Community datasets built from real tested pairs, most notably the Shared cM Project, put the average closer to 122 cM. The gap between theory and observation at this level is small and mostly comes from how segments are measured and reported.

The range is the important part. Reported totals for confirmed 2C1R pairs span roughly 14 to 350 cM. That is a twenty-five-fold spread for a single relationship. The reason is recombination: DNA is not divided evenly at each generation, so two siblings can pass down very different amounts to their descendants. One 2C1R pair sharing 40 cM and another sharing 300 cM is entirely normal.

Every figure in that table is an average that varies from pair to pair. Do not treat any of them as a threshold.

The good news at this degree: detection is essentially guaranteed. Unlike third and fourth cousins, where sharing zero DNA is common, a true second cousin once removed will show up as a match on any major test. If two people who should be 2C1R share nothing at all, the documented relationship is almost certainly wrong somewhere.

How It Shows Up in a DNA Match List

Your testing company will rarely say "2nd cousin once removed." It will give you a band of possibilities, and 2C1R will be one of several relationships inside it.

Expect labels like "2nd–3rd cousin," "1st cousin twice removed to 2nd cousin once removed," or a simple "2nd cousin" estimate with a confidence note attached. The prediction is generated from a shared centimorgan total, and totals overlap heavily between relationships.

Here is the specific problem at this level. These three relationships all have the same expected shared DNA of about 1.56%:

• Second cousin once removed
• Half second cousin
• First cousin three times removed

They are genetically indistinguishable by total centimorgans. No amount of staring at the number will separate them. What separates them is everything else:

Generation matching. A 2C1R sits one generation off from you; a half second cousin sits in your own generation; a 1C3R sits three generations off. Birth years across the whole match cluster usually reveal which pattern fits, even though individual ages prove nothing.

Shared matches. Look at who else both of you match. If your match shares DNA with your known second cousins on one particular line, the relationship almost certainly runs through that line.

The number of segments. A 2C1R typically shares its total across several segments. A half relationship at the same total often looks similar, so this is a weak signal on its own, but it is worth noting alongside the rest.

Trees. The reliable answer comes from documents. Find the great-grandparent couple you have in common and the relationship resolves itself.

At closer degrees, DNA totals separate relationships more cleanly. At more distant ones, like 1st cousin 2x removed, the same overlap problem appears with a different set of candidates.

What Their Children and Grandchildren Are

Once you have placed one person correctly, everyone descending from them follows automatically.

The jump from 2C1R to third cousin in the second row surprises people, but it is correct. Your parent's second cousin's child is at the same generational depth as you, both of you four generations below the shared couple. Four minus one is three, with no removal. Third cousins.

Half, Step, and In-Law Versions

A half second cousin once removed shares only one common ancestor instead of a couple, and shares about half the expected DNA.

This happens when the ancestral pair at the top is not a pair. If your great-grandmother had children with two different partners, descendants of those two lines are half relatives, and half relationships share roughly half the DNA of their full equivalents.

Step and in-law versions carry no shared DNA at all. Your second cousin once removed's spouse is your 2C1R by marriage, a real social relationship and a genealogically empty one. They will not appear on your match list, and if they do, you are related to them some other way.

What to Call Them

Call them "cousin," or use their first name. Nobody says "second cousin once removed" at a reunion.

The precise term is for genealogy, DNA analysis, medical family history, and legal paperwork. In everyday speech, families overwhelmingly simplify. Some use courtesy titles like "Aunt" or "Uncle" for the older-generation version, which is common and harmless as long as it does not end up written into a family tree as fact.

Other varieties of English handle this more gracefully than American English does. In South Asian English, "cousin brother" and "cousin sister" mark a cousin's gender and often imply closeness, a construction explained in cousin bro. American English has no equivalent and just leans on "cousin" for everything from a first cousin to a fourth cousin twice removed.

Frequently Asked Questions

What does 2nd cousin 1x removed mean?

It means second cousin once removed. The person is either your parent's second cousin or your second cousin's child, and the "1x removed" records that the two of you are one generation apart on the family tree.

How much DNA do second cousins once removed share?

About 1.56% on average, which is roughly 106 to 122 centimorgans. Real pairs range from about 14 cM to about 350 cM, so treat the average as a center point rather than a prediction for any particular pair.

Is my parent's second cousin my third cousin?

No. They are your second cousin once removed. Your parent's second cousin's child is your third cousin, because that child is in your generation rather than one above it.

Can a DNA test tell the difference between a 2C1R and a half second cousin?

Not from the shared total alone. Both average about 1.56%, as does a first cousin three times removed. Distinguishing them requires shared matches, generation patterns, and documented trees.

Do second cousins once removed always show up on a DNA test?

Essentially always. At this level, sharing no detectable DNA is so unlikely that a zero result usually means the documented relationship is incorrect rather than that the DNA simply did not pass down.

What is my second cousin once removed's child to me?

If the person is your parent's second cousin, their child is your third cousin. If the person is your second cousin's child, their child is your second cousin twice removed. The direction of the removal decides which answer applies.