Editing Identity by descent (section)

{{distinguish|text=lineage-bonded society or [[isolation by distance]], another concept in population genetics with the acronym "IBD"}}
{{short description|Identical nucleotide sequence due to inheritance without recombination from a common ancestor}}

A [[DNA]] segment is '''identical by descent''' ('''IBD''') in two or more individuals if:
* they have inherited it from a common ancestor without [[genetic recombination|recombination]], that is, the segment has the same ancestral origin in these individuals
* the segment is maximal, that is, it is delimited at both ends by ancestral recombination events.<ref>{{Cite journal
| last1 = Carmi | first1 = Shai
| title = A renewal theory approach to IBD sharing
| doi = 10.1016/j.tpb.2014.08.002
| journal = Theoretical Population Biology
| volume = 97
| pages = 35-48
| year = 2014
| pmid = 25149691
| pmc = 4179929
}}</ref>

[[File:Pedigree, recombination and resulting IBD segments, schematic representation.png|thumb|upright=2|alt=The origin of IBD segments is depicted via a pedigree.|The origin of IBD segments is depicted via a pedigree.]]

[[File:Pedigree, recombination and resulting IBD segments, schematic representation modified.png|thumb|upright=2|alt=The origin of IBD segments is depicted via a pedigree.|A colorblind-friendly version of this image.]]