Spatial genetic multiplicity

Spatial genetic multiplicity was what the Tenth Doctor used to explain how Gwen Cooper and Gwyneth looked similar. (TV: The Unquiet Dead, Journey's End)

Behind the scenes

 * Russell T Davies addressed spatial genetic multiplicity, explaining it as "not familial as we understand it. There's no blood tie. Spatial genetic multiplicity means an echo and repetition of physical traits across a time rift."