Simulating shared segments

Different types of relatives—for example, full siblings and first cousins—have different total shared segment lengths (in centiMorgans/cM) and different numbers of shared segments. Learning the patterns of how various kinds of relatives share DNA helps in identifying how two people are related. The simulator below is a web version of the open source program Ped-sim. It currently supports only a few relationship types, and if the type you are interested in is not here, feel free to contact us. A paper describing Ped-sim found that very distant relatives commonly share no DNA at all. (We will blog about this soon.)

To play with the paternal and maternal relative detector, you can simulate shared segments of a grandparent-grandchild or half-sibling pair below, then paste the segments on the detector page.


Random seed
(auto generates if blank)

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