Bateson, P. (1982). Preferences for Cousins in Japanese Quail. Nature, 295(5846), 236-237.
Early experience affects the mating preferences of many birds and mammals. The plasticity of behaviour is such that individuals reared with a member of another species may subsequently choose to mate with that species. Recent evidence suggests the most strongly preferred mates are slightly different from individuals that are familiar from early life. The implication of these findings is that an individual is able to strike an optimal balance between inbreeding and outbreeding by learning about its immediate kin and mating with a member of the opposite sex that is slightly different from its immediate kin. What such a balance might amount to in practice has previously been uncertain. I report here that Japanese quail of both sexes, having been reared with their siblings, subsequently prefer a first cousin of the opposite sex.