Genetic expression is one of the most fascinating processes of human biology.
Though you can often guess as to what a couple's offspring will look like, that's all it is -- a guess.
Though we know that genetic expression is, on the whole, a game of chance, we tend to assume things: Children will look like a mix of their parents, and siblings will look relatively similar to each other.
But that isn't always the case.
Take, for instance, the Aylmer sisters. Lucy has fair skin with freckles, red hair and blue eyes. And Maria? She's got gorgeous, abundant black curls, caramel skin and deep, brown eyes.
Oh, and they're biological twins -- amazing, right?
The girls' nearly opposite features can be traced back to their racially different parents. Their mother, Donna, is half-Jamaican while father Vince is white.
Lucy and Maria, 18, are the youngest of the Aylmer family, which also includes older brothers George, 23, and Jordan, 21, and sister Chynna, 22.
Our brothers and sisters have skin which is somewhere between Maria and I. We are at opposite ends of the spectrum and they are all somewhere in-between.
Having already had three similarly colored children, their mother was taken aback when Lucy and Maria were born.
It was such a shock for her because things like skin color don't show up on scans before birth. She had no idea that we were so different. When the midwife handed us both to her she was just speechless.
Because of their nearly opposite appearances, Lucy explains,
No one ever believes we are twins. Most twins look like two peas in a pod -- but we couldn't look more different if we tried. We don't [even] look like we have the same parents, let alone having been born at the same time.
As is common with twins, their personalities are quite different as well. Lucy, the self-described “shy one,” studies art and design at Gloucester College, while outgoing Maria studies law at Cheltenham College.
Though there were once drawbacks -- Lucy laments that “there was no way” the pair could ever swap identities -- both love their unique sisterhood.
Maria loves telling people at college that she has a white twin. And I'm very proud of having a black twin.
And they should be: There is nothing quite as beautiful as the unexpected.
Check out some photos of the fraternal twins below.