# Online Encyclopedia

# Family relationship

The **family relationship** between two individuals, where *G _{a}* and

*G*are the number of generations between the individuals and their nearest common ancestor, can be calculated by the following:

_{b}*x*= min (*G*,_{a}*G*)_{a}*y*= |*G*-_{a}*G*|_{b}

- If
*x*=0 and*y*=0 then they are the same person. - If
*x*=0 and*y*=1 then they are parent and child. - If
*x*=0 and*y*=2 then they are grandparent and grandchild. - If
*x*=0 and*y*>2 then they are great ... great-grandparent and great ... great-grandchild, with*y*−2 greats.

- If
*x*=1 and*y*=0 then they are siblings (brothers or sisters). - If
*x*=1 and*y*=1 then they are uncle/aunt and nephew/niece. - If
*x*=1 and*y*>1 then they are great ... great uncle/aunt and great ... great nephew/niece, with*y*−1 greats.

- If
*x*>1 and*y*=0 then they are*x*−1^{th}cousins. - If
*x*>1 and*y*>0 then they are*x*−1^{th}cousins*y*times removed.

So two people sharing a pair of grandparents have *x*=2 and *y*=0 and are described as being *first cousins*.

If *x*>0 and they only share one nearest common ancestor rather than two, then the word "half" is sometimes added at the beginning of the relationship.

Last updated: 10-24-2004 05:10:45