A first cousin once removed is someone who shares a set of grandparents with you but sits one generation above or below you on the family tree. The clearest examples: your parent’s first cousin is your first cousin once removed, and so is your first cousin’s child. The word “removed” marks a generational gap, not emotional distance or a weaker branch of the family.
How the Relationship Works
Start with standard first cousins. Two people are first cousins when they share the same pair of grandparents but have different parents. They sit on the same generational rung. Now picture one of those first cousins having a child. That child and the other first cousin are no longer on the same rung. The child sits one step lower, which makes the relationship “once removed.”
The removal runs in both directions. Your mother’s first cousin is your first cousin once removed because you’re one generation below the cousin tier your mother occupies. Flip it: your first cousin’s daughter is also your first cousin once removed, because she’s one generation below you. In each case the shared ancestors are the same pair of grandparents, but one person is a grandchild of those ancestors while the other is a great-grandchild.
“Removed” is purely a generation counter. “Once” means one generational step apart. “Twice removed” means two steps, and so on. The “first” in “first cousin” refers to the type of cousin relationship anchored to shared grandparents, not to the number of removals.
How to Count the Removal
The method is straightforward once you see it in action. Identify the most recent common ancestors for both people. For a first-cousin relationship, that’s a shared set of grandparents. Then count how many generations separate each person from those ancestors.
Say Person A is the grandchild of John and Mary (two generations down). Person B is the great-grandchild of John and Mary (three generations down). Person A sits two steps from the common ancestors; Person B sits three. The smaller number sets the cousin type: two generations down from shared grandparents means “first cousin.” The difference between the two counts (3 minus 2) gives you the removal. So they’re first cousins, once removed.
If Person B were four generations down instead of three, the difference would be two, making them first cousins twice removed. Age has nothing to do with the calculation. A 70-year-old great-grandchild and a 25-year-old great-great-grandchild of the same ancestors follow the same rules.
First Cousin Once Removed vs. Second Cousin
This is where most people get tripped up, and the two relationships are genuinely different. Second cousins share the same great-grandparents and sit on the same generational level. Their parents are first cousins to each other. A first cousin once removed shares regular grandparents with the other person but occupies a different generation.
A quick way to keep them apart: same level with shared great-grandparents equals second cousins. Different level with shared grandparents equals first cousins once removed. If you both have to go back one extra generation to find the common ancestors and you’re standing on the same rung, you’re second cousins. If one of you is a rung off and the shared ancestors are grandparents, you’re first cousins once removed.
What DNA Tests Show
DNA testing has become one of the fastest ways to confirm or discover this relationship. First cousins once removed share about 6.9% of their DNA on average, with a typical range of 3.2% to 11.5%.123andMe Customer Care. Average Percent DNA Shared Between Relatives That range is wide enough that testing companies sometimes list multiple possible relationships for a single match. A result around 6% could point to a first cousin once removed, a half first cousin, or a more distant relationship entirely.
Context resolves the ambiguity. If you already know one person’s place on the family tree, the shared percentage narrows down where the match fits. Without that context, the number alone won’t tell you the specific relationship. Even basic family records (names, birth years, locations) paired with the DNA result almost always settle it.
Confirming the Link Through Records
Working it out on paper starts with identifying the shared grandparents by full legal name and birth year, then documenting each generation’s parentage down to both people. Birth certificates and census records are the strongest evidence because they name parents directly. Where official records are missing, church baptism and marriage records, family Bibles, obituaries listing survivors, and military service records can fill in the chain. You’re building an unbroken line from the shared grandparents to each individual, generation by generation, so the step count can be verified.
Why the Label Matters for Inheritance
Courts classify family relationships using numbered degrees that measure how many generational steps separate two people through their nearest common ancestor. Under the civil law method used in most American jurisdictions, you count one degree for each step up to the common ancestor and one for each step down. For a first cousin once removed, that’s two steps up to the shared grandparents and three steps down, totaling five degrees of kinship. Standard first cousins sit at the fourth degree.
That one-degree difference matters when someone dies without a will. State intestate succession laws distribute assets in order of closeness, and a fifth-degree relative stands further back in line than a fourth-degree one. In practice, a first cousin once removed will inherit under intestacy only if no spouse, children, parents, siblings, nieces, nephews, or first cousins survive the deceased.2Justia. Intestate Succession Laws The general pattern starts with spouse and children, then parents, then siblings and their descendants, then grandparents and their descendants (aunts, uncles, first cousins), with first cousins once removed trailing standard first cousins in that last group.
Gift and Inheritance Tax
Federal gift tax rules don’t change based on your relationship to the recipient. For 2026, you can give up to $19,000 per person per year without triggering any gift tax reporting requirement.3Internal Revenue Service. Frequently Asked Questions on Gift Taxes Anything above that counts against your lifetime basic exclusion, which for 2026 is $15,000,000.4Internal Revenue Service. Estate Tax
State inheritance taxes are where the relationship bites. The handful of states that impose an inheritance tax group beneficiaries into classes by kinship. Spouses and children usually pay little or nothing. Siblings pay a moderate rate. Distant relatives like first cousins once removed almost always fall into the highest bracket, sometimes 15% or more on inherited assets. If you’re expecting an inheritance from a distant relative in one of those states, the tax can be large enough to shape your planning.
Can First Cousins Once Removed Marry?
Marriage between first cousins once removed is legal in the large majority of states. Roughly 25 states restrict marriage between first cousins, but most of those statutes target first cousins specifically and do not extend to the once-removed relationship. A few states define prohibited relationships broadly enough that more distant cousin marriages could be affected, so checking your state’s marriage statute before applying for a license is the safe move.
The genetic concern behind cousin marriage restrictions is the chance of both parents carrying the same recessive gene variants. First cousins once removed share roughly 6.9% of their DNA on average, compared with about 12.5% for first cousins.123andMe Customer Care. Average Percent DNA Shared Between Relatives That lower overlap is one reason legislatures have historically treated the once-removed relationship with less concern than standard first-cousin pairings.