Before 1967, it was illegal in 16 American states for a black person and white person to marry. Right wing groups on both sides of the Atlantic continue to espouse that the mixing of races is destructive and against some kind of natural order. Aarathi Prasad, a geneticist and mother of a mixed race child, sets out to challenge the ideas of racial purity and examines provocative claims that there are in fact biological advantages to being mixed race.