The question came up again the other day: “What is a second cousin?” And, since my old website will be going the way of the dodo soon, I thought I’d resurrect an old post here …

I know, as far as brain teasers go, it’s pretty bland stuff, and odds are good a simple web search would turn up a couple hundred pages of explanation – but it’s kind of a fun topic and I get to dust off a pretty cool chart.

Generally speaking, I describe a “cousin” is any blood relative who is not:

  • directly in line with me (parents, children, grandparents, grandchildren, etc),
  • one of my siblings
  • a sibling of one of my ancestors (uncles & aunts), or
  • a descendant of one of my siblings (nieces & nephews).

In the chart below, my cousins are all those relatives surrounded by the dotted line (that’s me over on the left).


Abbreviations: P=Parent, S=Sibling, Ch=Child, G=Grand, GG=Great-Grand, U=Uncle/Aunt, N=Niece/Nephew, Cs=Cousin, R=Removed

When my cousin and I have a common ancestor who is not our grandparent, we are second (or third, fourth, etc) cousins. The easiest way to figure out the ordinal is to count the number of generations between us and our common ancestor – my second cousin and I each have two generations (our parent and grandparent) between us and our common ancestor (our great-grandparent).

Cousins are “removed” when they aren’t of the same generation – the distance to our common ancestor is unequal. My cousins “once removed” are one generation from mine; two generations would be “twice removed,” and so forth. I’ve heard it counted either direction, but I prefer to start with the cousin closest to our common ancestor and then add “removed” to count generations to the cousin furthest from our common ancestor. So, my “first cousin once removed” could be either my grandfather’s great-grandchild, or my great-grandfather’s grandchild.

After explaining all of this, I often get asked if it really matters. To which I reply that when I attend our family reunion, I usually think of just about everyone in the room as my cousin – and some of them aren’t even blood relatives. But, it’s a lot easier to be liberal with your definitions over fried chicken and your aunt’s apple pie.

Originally posted 28 March, 2012