disassortative mating

[ dis-uh-sawr-tuh-tiv ]
/ ˌdɪs əˈsɔr tə tɪv /

noun Animal Behavior, Psychology.

the reproductive pairing of individuals that have traits more dissimilar than would likely be the case if mating were random (contrasted with assortative mating).
Compare panmixia.

Origin of disassortative mating