All your theories are belong to us
Theory 1: Luke Skywalker
The biggest and most probable theory is that Rey's father is Luke Skywalker. Her mother is unknown, but not extremely important (sorry, it's not Mara Jade, the EU/Legends is dead).
- Star Wars is always about the Skywalkers; the prequels focus on Anakin and the original trilogy focuses on Luke. It would make sense for the sequel trilogy to focus on the next Skywalker, offspring of Luke or Leia. In this case it would probably be Luke as he is the Skywalker previously focused on, though Leia is possible. So since TFA seems to focus on Rey, she would be Luke's daughter.
- Rey is extremely strong with the Force. She flew the Falcon better than Han, resisted Kylo's mind probing (even turning it back on him), and made Kylo look like a kid in a lightsaber duel. She never even had any training (for the Force and lightsaber combat; she actually had had experience with the Falcon). Kylo is strong in the force because he is Leia's son. And the only person stronger in the Force than Leia would be Luke. Therefore, the only person stronger than Leia's kid (besides Luke himself) would be Luke's kid. All the other Jedi are dead, remember. So Rey is probably Luke's kid.
- She grew up on a desert planet, not knowing her father and having no hope of a future. She gazes longingly at a ship taking off and hopes to explore the stars someday. Sound familiar? Yes, she is an almost exact parallel for Luke and Anakin. This further supports the notion that she is the next Skywalker for the trilogy.
- The lightsaber calls to her. This lightsaber belonged to - you guessed it - Luke and Anakin both, at one time or another. When she picks it up she has a vision of the hallways below Cloud City, which is where the lightsaber was last seen. She is having a vision from her father Luke, and her father and grandfather's lightsaber calls to her: yep, she's probably Luke's little girl.
- She was abandoned/hidden on a desert planet. Recall that Luke was put on Tatooine where the Empire would not find him, and Obi-wan was nearby to watch him. Rey was probably placed on Jakku for her own protection, so that the First Order would not find her. And as for Obi-wan watching over Luke: Lor San Tekka was probably watching over Rey (he is the guy that gives Poe the map and is promptly struck down by Kylo).
- Disney Infinity 3.0: Force Awakens Play Set. OK, OK, this one has been disproven, but it's interesting anyway. In the boss fight for the Disney Infinity play set, you are Rey fighting Kylo. Kylo spews random phrases at you, one of which sounds like "Face me, cousin!" The Internet exploded after this was discovered, believing that the game confirmed Rey being Luke's daughter nad Kylo's cousin. But when people paid closer attention, he was saying "Face me, coward!" or "Face me! Curses!" Still, Disney could have done this intentionally to lead us in the right direction.
- She finds a droid, which leads her to someone with potential romantic interest. Rey discovers BB-8 who leads her to Finn, who probably has a crush on her. When Luke bought R2-D2, the droid led him to Leia, who he at first liked in a romantic way. Of course, she ended up being his sister, but still, Rey has yet another Luke parallel.
- Rey gives the lightsaber to Luke, and the look on his face is almost one of surprised recognition. Also, it would be very symbolic for her to return her father's lightsaber to him.
- Jedi are forbidden to marry. Luke would have had to have broken the Jedi Code if he fathered Rey. Of course, his father did this with Padme and had Luke and Leia, but you would think Luke would learn from his mistakes. When Anakin had kids, the result nearly destroyed the galaxy. Luke should be smart enough to realize this. So Rey should be the kid of non-Jedi.
- Rey vs. Kylo is obviously going to be one of the central struggles in the sequel trilogy. And a struggle between cousins seems a little weird, right? I mean, if JJ Abrams is going to make it a family struggle, he may as well make it between siblings... or even twins? (Jacen and Jaina confirmed!)
Theory 2: Han and Leia
The biggest theory prior to TFA's release was that Rey was the child of Han and Leia.
- A sibling/twin struggle makes perfect sense, and would be a nod to the EU/Legends. And the way Kylo says, "What girl?" coupled with his prioritizing Rey's capture over BB-8- he must know who she is. Of course, this could support the Luke theory and say that he recognizes his cousin, but he is far more likely to remember his twin sister than his cousin.
- Han is the "father that Rey never had". She instantly bonds with him, and they even finish each other's sentences. Plus she loves the Falcon. And Han offers her a job. They are so alike that it only makes sense for Han to be her father, and the Falcon to be a family heirloom. And oh yeah, "Chewy loves her".
- Leia never gives the slightest indication of recognizing Rey, and you would think she would recognize her own daughter. Still, it is possible that Rey was stolen at birth, even though she arrives on Jakku at 5 or 6.
- Han (SPOILER ALERT) dies. If he were her father, JJ Abrams would probably have given them one last moment of realization- he would realize who his daughter was and she would be able to spend a few final moments with her father as a father before he dies. If Han really is Rey's father, it seems a little insensitive for him to never find out and her find out well after he is dead.
- Leia is not that strong with the Force, so how is Rey this incredibly strong if she is Leia's daughter. This can be explained away by saying the Force is a passive gene, but still, if it were a passive gene, Leia would not have had it and Rey would. Leia does have ti, just not as strong, but I do not believe that there is a passive gene for increased force sensitivity.
Theory 3: Obi-wan
A more recent theory is that Rey is the granddaughter of Obi-wan Kenobi.
- In Rey's vision, Obi-wan talks to her. He says "Rey" (Alec Guinness) and "These are the first steps" (Ewan McGregor). Of course her father would call to her.
- Wouldn't it be great for Luke to train the granddaughter of the guy who trained him?
- Obi-wan having kids would be a violation of the Jedi Code. It is easily dismissed for Luke to violate the Jedi Code, as he does not necessarily know the code: the Empire would have destroyed all records of it (Unless Lor San Tekka uncovered something about it). However, Obi-wan knew the code very well and knew better than anyone what love had done to Anakin. It is hard to imagine him deciding to break it after what happened to Anakin. Unless... he had a kid before the Clone Wars. Obi-wan once fell in love with Dutchess Satine (later executed by Darth Maul), and could have unknowingly made her pregnant. She could have hidden their child without his knowledge in order to protect him from expulsion from the Jedi Order. Obi-wan once told Satine he would leave the Order for her, so it is not a stretch for the two to have had kids.
Theory 4: Luke/Obi-wan
This theory is just a combination of Theories 1 and 3. It uses the overwhelming evidence of Luke being Rey's father and pairs it with Obi-wan being the one calling to Rey. In her vision, she sees from Luke's perspective but hears Obi-wan's voice. It makes sense for these two to be her father and grandfather, if Luke married Obi-wan's daughter.
Theory 5: Thane and Ciena
My personal favorite, but also not a very likely theory. It is based off of the book "Lost Stars" by Claudia Gray. If you have not read it, do so. It's amazing.
- The description of Ciena is fairly similar to Rey. Strong, muscular, black hair... it doesn't prove it but it helps.
- Rey lives on Jakku. The planet's only significance is the battle that happened there in 5 ABY. Now, Luke was placed on Tatooine by Obi-wan because it had significance to his parents; namely, Anakin grew up there. So you would think Lor San Tekka would have placed Rey on Jakku for some special significance, maybe one that relates to her parents. And since Jakku means nothing without the battle, the reason for Rey to be placed there must be tied to the battle. Hmm. Lor San Tekka could have just said, "There was a big battle here, so Rey should live here." But this is Star Wars. Everything is symbolic. So what happened at the Battle of Jakku? There are literally only three people tied to the battle in the books: Wedge Antilles, Thane Kyrell, and Ciena Ree. Wedge flew his X-wing, while Thane and Ciena had a big fight on the bridge of the Inflictor. The ship ended up crashing and is - you guessed it again - the Star Destroyer from the trailer and the one Rey scavenges in. So If Thane and Ciena are Rey's parents, they would have every reason to put her on Jakku, and how symbolic for her to survive off of the very ship that her mother crashed?
- Neither Thane nor Ciena are said to be Force-sensitive, but that doesn't mean they aren't. In fact, Ciena is a strong believer in the Force and says that it is what keeps bringing Thane and Ciena back together again. This makes sense- they always have random encounters, seemingly by luck- but it's a big galaxy. The Force is definitely guiding them and their relationship. It would be no surprise if one or both of them were revealed to be able to use the Force. Just because they haven't unlocked their abilities yet doesn't mean they don't have them. In fact, Rey's Force abilities were locked away until Kylo Ren unlocked or awakened them, hence the name of the movie. This could be a genetic trait, right? Force abilities locked away? And in the book, Thane and Ciena are both outstanding pilots and can detect what each other are going to do before they do it- sounds a lot like the Force to me. So Rey could still be strong with the Force, even if Thane and Ciena are not revealed to be. And as stated in the "None Theory" below, parents do not have to be Force-sensitive for the child to be so.
- But where are Thane and Ciena? Ciena was a female captain in the Empire, and even though she leaves in the end, in was unvoluntary and she still believes she owes an oath of loyalty to them. So if the Empire popped up again, perhaps as the First Order, Ciena would be likely to join back up, and they would probably welcome her with open arms- the Empire viewed her as a heroic martyr when Thane pulled her from the ranks during the Battle of Jakku. So if Ciena joined the First Order, which she probably would, she would be a highly respected/feared female captain... While possible that Ciena is Captain Phasma (which would explain why Thane hid her on Jakku under Tekka's supervision) one major difference remains, and there is nothing racist about it. Ciena is desribed as light brown in complexion, and even a stretch would place her as very much tanned. But Gwendoline Christie, who plays Captain Phasma, is very much white. And even then, Ciena is 54 years old in TFA, which would be a little old for a stormtrooper, even a high-ranking one.
- Where is Thane? If Ciena is not Phasma, why did they abandon their kid? Lor San Tekka cannot be Thane: he is described as "having seen the Clone Wars with his very eyes" and Thane was born on Empire Day (so were Ciena, Luke, and Ezra).
- Thane and Ciena are from the books, and Lucasfilm seems to be keeping films and books separate. While this is stupid, they do it anyway and even if Lost Stars was a backstory book, it would have been released after Episode VIII or IX.
- There is simply too much evidence supporting other theories. Unless Abrams purposefully tried to throw us off the trail...
Theory 6: Anakin Reincarnate
Anakin was conceived by the Force. What if Rey is too? Maybe that's why her parentage is so obscure: there isn't one. Of course Anakin still had a mother to birth him, and Rey would need one as well; a random woman who doesn't want a kid and so dumps the kid on Jakku. This would explain why Maz tells Rey "They're never coming back." Rey's mom does not want her. So maybe the Chosen One prophecy is a cycle? Anakin was conceived by the Force, brought balance to it, and died. When the galaxy goes out of balance again, he is reborn, again by the Force, as Rey. It explains all the similarities between her and Anakin: they are the same person. Also Luke's look of recognition: he recognizes his father, but in a different body. This theory is a little far fetched, but makes some sense. Rey is the next Chosen One, but also the same one. Makes you wonder if Anakin wasn't the first.
Theory 7: None
The theory says that Rey's parents do not matter. She could have learned the ways of the Force without genetics; after all, Luke once asked Han why he was not a Jedi. Han's answer was not, "My parents weren't Force-sensitive", but "I don't believe in that stuff". And in the Clone Wars, we see kids with high midi-chlorian counts popping up everywhere. Rey could easily be someone random with a lot of midi-chlorians. While the prequels are still canon and the midi-chlorians could be a factor, it seems unlikely that JJ Abrams would draw on a hated aspect of the prequels to explain Rey. In fact, the reason midi-chlorians are hated (or one of the reasons) is because anyone should be able to learn the Force, not just the lottery winners. So by making Rey a random person with low midi-chlorian levels and yet extremely strong in the Force, JJ Abrams would be flipping the prequels off, much to the delight of prequel haters everywhere.
Theory 8: New characters
This theory states that Rey's parents are important, but we just have not met them yet. They are entirely new characters to the franchise, just as Rey is herself.
Theory 9: Lando?
Finn and Rey quickly bond. It could be a romantic thing, or it could be a sibling thing. What if Rey is Lando's daughter and Finn's sister? Assuming, of course, that Finn is Lando's boy. The Amazon leak was false, but it could be true.