First, Second, Third Cousins etc
The easiest way to work out the type of cousin you have is to trace back to a common ancestor.1
Rule 1. Count the number of ‘greats’ in your common ancestors. Add one.
For example, if you share a grandparent, there are no ‘greats’, so add one to zero and you get one. You are FIRST cousins
If you share a great grandparent there is one great. Add one and one. You are SECOND cousins.
So, relatives who share a grandparent are FIRST COUSINS.
Relatives who share a great grandparent are SECOND COUSINS.
Relatives who share a great great grandparent are THIRD COUSINS.
And so on.
Clear? We’ll move on to cousins REMOVED next.
Cousins ‘Removed’
The examples given in Rule 1 apply to kin who are in the same generation level. If there is a generational difference then an additional rule is applied.
Rule 2. Count the number of generations that are different and express the relationship as that number ‘removed’.
For example, if you and another person share the same ancestor but there is one generation difference between you in the linkage to that ancestor, you express the relationship as ‘ONCE REMOVED’.
If there are two generations difference, that cousin is ‘TWICE REMOVED’, and so on.
Let’s say John and Mary share the same ancestor, Bridget. Bridget is John’s grandmother but she is Mary’s great grandmother. John and Mary are first cousins once removed.
If Bridget was Mary’s great great grandmother, John and Mary would be first cousins twice removed.
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- I am referring here to the conventions used in English systems. Other societies may have different ways of reckoning cousin relationships. The English system of kin terminoloy is referred to as the Eskimo or Inuit system. ↩︎
