Cousin Chart: What Second Cousin Once Removed Actually Means

Ever wondered what a "second cousin once removed" actually means? Or how your children are related to your first cousins' children? The language of family relationships sounds like legal jargon, but behind it is simple arithmetic.

Here is a plain-English guide to cousin relationships, what "removed" means, and a cousin chart you can come back to.

Direct line and collateral line

Every relationship on a family tree is one of two kinds:

• Direct line: people directly above or below you — parents, grandparents, children, grandchildren. There is no degree to work out; it is just a number of generations.
• Collateral line: everyone who shares an ancestor with you but is not directly above or below you — siblings, aunts, uncles, cousins. This is where "cousin", "removed" and "great-" do the work.

How cousin relationships work

• Cousin degree (1st, 2nd, 3rd) tells you how far back your most recent common ancestor is:
  • 1st cousins share grandparents.
  • 2nd cousins share great-grandparents.
  • 3rd cousins share great-great-grandparents.
• "Removed" (once, twice) tells you how many generations apart the two of you are:
  • If your cousin is in a different generation from you (for example your first cousin's child), they are "removed".
  • Once removed = one generation of difference.
  • Twice removed = two generations of difference.

The cousin chart

Find the ancestor you share, then how many generations each of you is below them:

| Common ancestor | Your generation | Their generation | Relationship | | :--- | :--- | :--- | :--- | | Grandparents | Grandchild | Grandchild | 1st cousins | | Grandparents | Grandchild | Great-grandchild | 1st cousin once removed | | Grandparents | Grandchild | 2nd great-grandchild | 1st cousin twice removed | | Great-grandparents | Great-grandchild | Great-grandchild | 2nd cousins | | Great-grandparents | Great-grandchild | 2nd great-grandchild | 2nd cousin once removed | | Great-great-grandparents | 2nd great-grandchild | 2nd great-grandchild | 3rd cousins |

"Once removed" works in both directions

Going down: your first cousin's children

You and your first cousin share grandparents. Your first cousin's child is one generation younger than you, so they are your 1st cousin once removed.

(In casual conversation people often call them "second cousins", but genealogically that is not right. Your children and your cousin's children are the actual second cousins.)

Going up: your parents' first cousins

Your parent and their first cousin share grandparents (your great-grandparents). Your parent's first cousin is one generation older than you, so they are also your 1st cousin once removed.

Half-, step- and in-law relationships

The other place trees get tricky is relationships that are not purely by blood:

• Half- relationships share exactly one biological parent, not two. A half-sibling connects to the one shared parent.
• Step- relationships come from a parent's marriage. A step-sibling shares no biological parent with you; the connection runs through the marriage, not through birth.
• In-law relationships come through your own or a relative's marriage — your spouse's brother is your brother-in-law.

These distinctions change what a chart should show. Draw a step-sibling as a sibling and the chart quietly claims a blood relationship that does not exist; how to chart a blended family tree covers the layout side.

Cousin marriage and pedigree collapse

In many family histories — from European royal houses to Muslim and South Asian lineages — marriages between first or second cousins have been common. When cousins marry, their descendants reach the same ancestor by more than one route, which genealogists call pedigree collapse.

Charting a cousin marriage means one woman belongs in two places at once: as her father's daughter and as her husband's wife. In Blaadline she appears in both places on purpose, because both are true, rather than one of the two facts being hidden.

Let the tree name your relatives

Working out a relationship in your head is error-prone. In Blaadline, select anyone and the side panel names the people around them — parents, grandparents on each side, uncles and aunts by which side they are on, first cousins, nieces, nephews and in-laws — in English or Bengali. It does not yet name second cousins or "removed" relationships; for those, use the chart above.

New to genealogy? Start with our guide on how to make a family tree.