4 reports "Geneticist Aarathi Prasad considers the theory that mixed-race humans are blessed with innate advantages, something farmers recognise in plants and animals as hybrid vigour. This idea is regarded as repellent by both dingbat racists and, as Prasad discovers, by many mixed-race people who object to being defined by their skin colour.. Before 1967, it was illegal in 16 American states for a black person and white person to marry.