The rate of identical-by-descent segment sharing between close and distant relatives.

ABSTRACT: Genetic relatives share long stretches of DNA they co-inherited from a common ancestor in identical-by-descent (IBD) segments. Because children inherit half their parents' genomes, the expected amount of DNA relatives share drops by 12 for each generation that separates them, being 2^-d for d-degree relatives. Even so, there is substantial variance in sharing rates so that most distant relatives share zero IBD segments. I characterized IBD segment sharing between relatives by simulating 100,000 pairs for each of first through eighth cousins, including once-removed and half-cousins, while modeling both crossover interference and sex-specific genetic maps. My results show that 98.5% of third cousins share at least one IBD segment, while only 32.7% of fifth cousins and 0.96% of eigh

SUBMITTER: Williams AL 

PROVIDER: S-EPMC12930157 | biostudies-literature | 2026 Feb

REPOSITORIES: biostudies-literature