The Bible just drops them into the story. Where did they come from? It's one of those questions that has kept Jewish tradition busy for millennia.

The simple answer? Adam and Eve didn't waste any time. According to some traditions, the very day they were created, they… well, they got to work. And they were productive. Really productive.

One legend, found in Genesis Rabbah (22:2-3), paints quite the picture. Two went into the bed, the story goes, and seven emerged! Apparently, Cain was born with a twin sister, and Abel arrived with two sisters. Talk about a full house!

So, Cain married Abel’s twin, and Abel married Cain’s. Problem solved, right? Not so fast. The real trouble, according to some, came with Abel's second twin sister. What was to become of her? Who would she marry? They couldn't agree on her fate.

In fact, some say she was the subject of the dispute between the two brothers. As the story goes, it was out of this disagreement that Cain slew his brother Abel, and the voices of the blood of the families who were destined to issue forth from Abel cried out before God. Talk about sibling rivalry gone wrong!

Now, the Book of Genesis itself doesn't explicitly tell us what Cain and Abel fought about. That’s where these stories, these midrashim, come in. They fill in the gaps, offering interpretations and possibilities. And one of the most common explanations, as you might guess, is that they were fighting over a woman.

In some versions, it's specifically Abel's second twin that caused all the trouble. Other accounts, like in Genesis Rabbah 22:7, suggest the woman they fought over was actually the "first Eve" — a reference to earlier traditions of a first wife of Adam who preceded Eve.

And there's more! Some midrashim even imply that Cain and Abel were twins themselves, though the biblical text doesn’t explicitly state that.

We even get names for these wives! Sefer ha-Zikhronot, the "Book of Remembrances," identifies Cain's wife as Kalmana, and Abel's wife as Deborah. This same text also says that these women were their twins. This contrasts with the interpretation where Cain and Abel each marry the other's twin.

So, what does it all mean? Well, these stories remind us that the Bible isn't always a straightforward narrative. It's full of gaps and ambiguities that invite us to explore, to interpret, and to imagine. And sometimes, the most interesting stories are the ones that fill in those gaps, even if they contradict each other. It’s a reminder that the human story, even from its very beginning, is complex, messy, and full of questions that don't always have easy answers.