这对可爱的双胞胎姐妹名叫卡拉尼和加拉尼。尽管两人肤色大不相同—--卡拉尼皮肤白皙，而加拉尼的肤色较深--但她们确实是双胞胎。
These adorable baby girls are Kalani and Jarani Dean. Despite their different appearances -- Kalani has light skin and blue eyes, and Jarani has dark skin and brown eyes -- they are actually twins.
她们的父母惠特尼·迈耶和托马斯·迪恩来自伊利诺伊州昆西市。去年4月这对双胞胎刚出生时，迈耶就发布了这对双胞胎的独特照片。
The girls' parents are Whitney Meyer and Tomas Dean, from Quincy, Illinois. Meyer has been posting pictures of the unique pair since they were born last April.
显然，他们不敢相信自己的运气。
The couple obviously couldn't believe their luck.
迈耶在接收CNN下属部门KHQA的采访时表示：“她们刚出生时，我真的不敢相信！这是如此罕见，我不相信会发生我的孩子身上。”
"At first when they were born, I wanted to believe it but it's so rare I didn't think it'd happen to my twins!" Meyer told CNN affiliate KHQA. "But sure enough they're biracial twins!"
迈耶是个白人，而迪恩则是黑人，这解释了此种现象的部分原因：
Meyer is white and Dean is black, which explains part of this phenomenon.
两个孩子是异卵双胞胎--两个受精卵发育而成的科学术语。所以是由两个不同的卵子分别与两个精子结合而成（而单卵，或者同卵双胞胎，是由一个受精卵分裂而成的两个胚胎）。
The twins are dizygotic, which is just the scientific term for fraternal twins. So each baby girl started out as a separate fertilized egg (monozygotic, or identical twins, start off from the same egg and then divide).
在异卵双胞胎中，每个胚胎会遗传父母不同的基因组合，所以如果父母是不同的人种，那么孩子就极有可能会遗传不同的肤色基因。
In a fraternal twin situation, each baby inherits a different combination of genes from mom and dad, so when the parents are of different races, it is possible the inherited genes for skin color can differ.
然而，这种显著的不同仍不多见。遗传学家吉姆·威尔森在接受BBC采访时表示，在英国生双胞胎的混血夫妻中，这种肤色不同的概率仅仅是1/500。
Still, the striking occurrence is rare. Geneticist Jim Wilson told the BBC that for mixed-race couples in Britain who are expecting twins, there is about a one in 500 chance that their babies will be born with different colored skins.