After seeing "Star Wars: The Force Awakens" twice over the last three days, I've had a lot of opportunity to digest the biggest question the movie left everyone with.

The biggest question: Who is Rey?

There's a lot of early speculation, but after taking more time to think about it, I think a common theory about Rey is likely true.

I'll explain why below, but don't even think about reading more if you haven't seen the movie yet. It's all spoilers from here.

rey star wars force awakens Talk about a sibling rivalry! Disney/Lucasfilm

Here's the theory: Rey is Kylo Ren's sister. We learn relatively early on in the movie that Kylo Ren is the son of Han Solo and Leia Organa. Kylo (his real name was Ben Solo before turning evil) showed early signs that he was strong in the Force, but was leaning towards the Dark Side. So Leia and Han decided to send him off to train with Luke Skywalker, who was working on building a new generation of Jedi. 

Somehow, Kylo was seduced by a mysterious figure named Supreme Leader Snoke, and he decided to turn against Luke. Luke takes his failure to control Kylo personally and goes into hiding, giving Kylo and the new evil group the First Order a chance to increase in power and threaten the Republic.

So what does that have to do with Rey?

Here's my theory for Rey's back story:

Han and Leia had two kids: Ben Solo and Rey Solo.

Ben is a few years older than Rey. Ben was somehow seduced by Snoke and turned to the Dark Side, becoming Kylo Ren. He killed the Jedi training under Luke, and forced Luke to go into hiding. Han and Leia had no choice but to hide the five-year-old Rey from Snoke and Kylo because she'd be an obvious target for them. So they had her dumped on the remote world of Jakku to fend for herself. That forced Kylo and Snoke to spend all their time hunting Luke instead of an easy target like Rey.

han solo star wars Disney/Lucasfilm

Kylo was too busy turning to the Dark Side to ever know Han and Leia had another child. Remember, Han and Leia sent Kylo away to train with Luke when he started showing signs he couldn't control the darkness in him. He probably had no contact at all with his parents during these years. After Kylo turns, Han and Leia are forced to pretend they never even had a second child in order to make sure she remains safe.

Now fast forward about 15 years to the events in "The Force Awakens". 

There's a lot of evidence pointing to the connection between Rey and Kylo.

In the third act of the movie, Rey discovers she has Force powers when Kylo attempts to probe her mind using the Force. It's as if these two have a special bond and Kylo's probing awakens the Force inside Rey. She quickly adapts to her new skills, and by the end of the movie she's able to hold her own against Kylo in a lightsaber battle.

Kylo also becomes especially interested whenever someone reports that the "girl" (Rey) is nearby and has the droid BB-8. He probably senses the connection with her early on, but doesn't quite know what to make of it.

There's also a ton of evidence that the other characters around Rey know who she is.

Rey and Han have a strong connection from the very beginning. They finish each other's sentences. Rey intuitively understands how the Millennium Falcon works, possibly better than Han. When Han learns Rey's name, he gives her a knowing look and offers her a job.

When Han and Rey visit Maz Kanata's cantina, there's a moment when Rey steps away from the table to talk Finn. Maz asks Han who Rey is, but before he can answer, the camera cuts away. We never learn what Han says.

But right after that, Rey feels Luke's old lightsaber calling to her from Maz's basement. If my theory is correct, Han probably told Maz that Rey is his daughter. Maz realizes the significance of that, and through her connection with the Force, she makes sure Rey finds the lightsaber. That'll lead Rey on a path to find Luke, become a Jedi, and put an end to all the madness.

lightsaber star wars force awakens Disney/Lucasfilm

Finally, there's the moment when Rey and Leia meet for the first time. They hug. This is obviously because of a shared remorse over Han's death, but I think it's also possible Leia is overwhelmed with emotion after seeing the daughter she abandoned more than a decade ago.

In short, everyone around Rey is lying to her about her origins. It's the same thing that happened to Luke in the original trilogy. Obi Wan, Yoda, and Luke's aunt and uncle knew Luke was the son of Darth Vader, but they deliberately kept the information from Luke to keep him safe. Even after Luke found out that Vader was his father, Obi Wan and Yoda didn't tell him that Leia was his sister. Luke had to figure that out for himself.

It seems like the same thing is happening to Rey. She won't find out her true origins until she has completed her training with Luke and has to confront Kylo Ren again.

There's one big caveat to my theory.

A lot of people think Rey could be Luke's daughter. I think that's also possible, but not as likely. But I'm going to hedge on my theory a bit so I don't look like a total fool in 2017 when "Episode VIII" comes out. 

If Luke met someone and had a child with her, it doesn't change the theory I detailed above too much. In that scenario, Luke hid Rey on Jakku to keep her safe from Kylo and Snoke, and only told Han and Leia about it. Everything else is pretty much the same.

UPDATE: A few days after I wrote this post, I learned some new information that backs up my theory. In response to a question on Twitter, LucasFilm creative executive Pablo Hidalgo confirmed that Kylo Ren is about 29 or 30 years old:

Kylo Ren age confirmation Twitter

And in the new "Star Wars Visual Dictionary" for "The Force Awakens," we learn that Rey is 19.

So it's very likely that because of their age difference, Kylo and Rey are unaware they are siblings. Kylo was sent away at a young age to train with Luke when he started showing signs he was slipping towards the Dark Side. A few years later, Han and Leia had Rey. And by the time Rey was five, things went south with Kylo and Han and Leia had no choice but to hide Rey on Jakku.