How did Rey become Force-sensitive? We examine the Canon texts
The reveal of Rey’s parents was one of the many reasons why fans were left feeling unfulfilled by the The Last Jedi. Of course it’s not uncommon in the galaxy far far away for a Force-sensitive child to be born from parents without the same powers: look at Anakin for example. But in The Force Awakens Rey repeated that she was waiting for someone; alluding to either a parent or someone else important. Despite Kylo Ren’s lack of explanation, in the canon texts some hints and clues are provided as to Rey’s childhood and abilities.
In number 10 of the Darth Vader comic book series, by Charles Soule, it is made clear that a list of Force-sensitive children was destroyed. Vader wanted to catch Jedi librarian Jocasta Nu in order to find this list. But in an act of anger and jealousy Vader destroyed this list so that he could remain as one of the last remaining Force wielding people. In one of Vader's most intriguing moments outside of the movies, he then lies to The Emperor about the death of Nu and the list. Vader’s act may well have led to Rey (or her parents) being undiscovered, despite the fact that she was hiding in “pretty much nowhere”, as Luke would say.
But Jakku is not just “nowhere”. It is the scene of the final battle in Star Wars Aftermath: Empire’s End where the Empire is finally defeated and retreat to the Unknown Regions. In this novel it is made clear that Palpatine has made a plan for the ‘Empire’s End’ and had already been searching for a safe route through the Unknown Regions. This is significant to Rey as one of the hidden bases in which The Emperor conducted his research was Jakku. Perhaps Disney wanted this planet introduced before The Force Awakens, but it seems strange they would pick this location unless there was a reason to it…
When the base is infiltrated and destroyed there is a huge burst of Force energy which is released. This was caused by the destruction of the Force-filled items which Palpatine collected, which were destroyed. Could it be possible that this burst of Force energy somehow impacted Rey? Unlikely. But it does reveal that the Force was strong in this area of Jakku, and as can be seen in The Force Awakens Rey lived close to where this battle took place. Could she somehow have gained her powers due to the proximity in which she lived to this base? Maybe she was always Force-sensitive, but living so near to the base added to her powers?
So, outside of what Kylo Ren stated, there are two plausible ways in which Rey developed her Force powers. But the ending of The Last Jedi seemed to indicate a different possibility: an option which is much more ‘Disney-fied’. With that unknown child using the Force to pick up the broom, perhaps there are countless Force-sensitive children still in the galaxy. Unlike the prequel’s view on the Force which suggested you had to be born with these powers, this scene (and the new Disney canon) indicates that it can be learned through mediation. This seems to be the way in which Rian Johnson wanted to go, but with J.J Abrams taking the reigns again for the final instalment of the trilogy, who knows where Rey’s heritage will go? But certainly seeds have been planted for some interesting ideas.