Is it farther or further?
c.1600, with -ure, from admix (1530s), a back-formation from admixt (early 15c.), from Latin admixtus "mixed with," past participle of admiscere "to add to by mingling, mix with," from ad- "to" (see ad-) + miscere "to mix" (see mix). In Middle English admixt was mistaken as a past participle of a (then) non-existent *admix. Earlier in this sense was admixtion (late 14c.).
marriage or cohabitation by persons of different race. Theories that the anatomical disharmony of children resulted from miscegenation were discredited by 20th-century genetics and anthropology. Although it is now accepted that modern populations are the result of the continuous mixing of various populations since prehistoric times, taboos on miscegenation-in some instances legally enforced-have existed and continue to exist in many race-based societies. In South Africa the official policy of apartheid for many years included legal prohibitions on miscegenation. In the United States many states had laws against interracial marriage until the Supreme Court declared them unconstitutional in 1967.