Meet Lucy and Maria Aylmer, two non-identical twins from Gloucester in the UK. Born to a Caucasian father and a half-Jamaican mother 18 years ago, the girls’ looks are a perfect example of how genetic material from both parents can end up being expressed in a child.

Unlike identical twins, where a single egg is fertilised by a single sperm before splitting into two identical halves, non-identical twins are formed when the mother released two eggs instead of one, and they’re fertilised by two separate sperm. So while identical twins will end up being the same sex, the same blood type, and have very similar looks - they’re technically clones of each other - non-identical twins will really only have the same likeness and genetic similarities as non-twin siblings.

What happened in the case of Lucy and Maria was that their mother is carrying the genes for both black and white skin, and Lucy ended up with the genes that encode white skin, and Maria, the genes that encode black skin.

Interestingly, many British African Caribbean people, like Lucy and Maria’s mother, are directly descended from Caucasian Brits, as a study conducted as part of a BBC documentary back in 2003 found, and this increases their chances of conceiving a child with white skin.

The researchers found that 27 percent of British African Caribbean men had white ancestry somewhere in their paternal line, and around 13 percent of the DNA inherited by British African Caribbean men and women did not originate from Africa, David Derbyshire reported for The Telegraph at the time. "Around 98 percent of men and women could trace their direct maternal ancestry back to Africa," said Derbyshire. "The remaining 2 percent had a 'mother line' that originated in Europe."

And while it’s interesting to see the beautiful differences in Lucy and Maria Aylmer, just this week, Bill Nye the Science Guy has being doing the rounds to promote his new book, Undeniable: Evolution and the Science of Creation, in which he talks about the idea that, scientifically speaking, there’s no such thing as race. He discussed this with Real Time with Bill Maher producer, Miles Leicher, saying:

"If you were to have sex with a woman from China - southern China, western China - all you’re going to get is a human. Sorry man, the only thing that’s going to come out is a human. That’s because we’re all one species. We are all one race, in a sense. The only difference is the colour of our skin, and that’s the result of where our ancestors lived on the Earth’s surface. ... There have always been tribes ... but what we have to appreciate now is that we live in a global community. And tribal loyalties… they’re not relevant to our future."

Also interesting in this interview is that Nye mentions he’s changed his mind about genetically modified (GM) foods - saying he’s now going to revise the relevant chapter in his new book. In the past, he’s said that there’s something fundamentally problematic with foods containing GMO crops, and has discussed his concerns about the potential environmental risks.

But having spent a lot of time with Monsanto scientists recently, he’s come out with a different view. "I’m very excited about telling the world. When you’re in love, you want to tell the world,” he said. Tell us now, Bill! We’ll have to wait till some time later this year for the chapter to be released, but you can watch the full interview below: