Identical by state
From ISOGG Wiki
Identical by state or identity by state (IBS) is a term used in genetics to describe two identical alleles or two identical segments or sequences of DNA. The terms identical by type or identity by type (IBT) are sometimes also used. In genetic genealogy the term IBS is generally used to describe segments which are not identical by descent and therefore do not share a recent common ancestor. IBS is also used in genetic genealogy to describe small IBD segments which are shared by many people both within and between populations and which have no genealogical relevance.
The techniques of triangulation, chromosome mapping, and phasing can be used to distinguish between IBD segments and non-IBD segments.
Blog posts
- Anatomy of an IBS segment by Ann Turner. A guest post on Jim Bartlett's Segmentology blog, 2 October 2015.
- Cooper K. When is a DNA segment match a real match? IBD or IBS or IBC?. Kitty Cooper's DNA Genealogy blog, 27 October 2014.
- Rose K. The ABCs of DNA - IBD vs IBS vs mIBC. DNA Genealogy blog, 30 January 2012. [Article snapshot from 2 May 2015.]
Further reading
- FTDNA definition of identical by state Family Tree DNA Learning Center
- Wheaton K. atDNA matches. Lesson 9 in the series "Beginners' Guide to Genetic Genealogy", Wheaton Surname Resources website, 2013.
- Turner A. "Satiable Curiosity: Identity Crisis: Identical by State or Identical by Descent?" Journal of Genetic Genealogy Fall 2011, Volume 7.