For what feels like such an expansive galaxy, Star Wars is actually a pretty small universe. The Skywalker family — Anakin, Luke, Leia, and now Kylo Ren and possibly Rey — are at the center of every important event during the most tumultuous time in the history of the galaxy.
But the interconnected nature of the Star Wars Universe doesn't stop there. C-3PO was built by Anakin Skywalker, who was later put in the service of Padmé Amidala, Anakin's future wife and mother of Luke and Leia.
R2-D2 was Anakin's droid — after serving as an astromech on Padmé's starship — for the duration of the Clone Wars, and would later be the droid his daughter selects to carry the Death Star plans, who then happens to be purchased by her brother's family.
Chewbacca was friends with Yoda, both of who would play a critical role in Luke's journey from farm boy to Jedi.
Anakin was buds with Greedo as a child, who would go on to be in the employ of Jabba the Hutt and ultimately meet his demise at the hands of Han Solo, who himself would later be tortured by Greedo's childhood friend Darth Vader.
Palpatine is from the same planet as Padmé, making it possible to meet Anakin and exploit his feelings to lure the boy to the Dark Side in the first place.
Boba Fett is basically the template upon which the Empire's forces were built, being an unaltered clone of his father Jango, giving him a far greater role in the shape of the universe than that of a mere bounty hunter.
And then there's the matter of Star Wars: Rebels, featuring a crew who is only one degree of separation between Princess Leia and Lando Calrissian, though the two characters never meet until The Empire Strikes Back.
And the list goes on.
It's part of the charm of Star Wars that it feels personal yet still so immersive. By nature, much has been made about the parentage of Rey in The Force Awakens, a question that won't be answered for quite some time yet, and wouldn't be a total surprise if she turned out to be a Skywalker.
With the release of the Rogue One trailer, of course there are theories sprouting up that Felicity Jones's Jyn Erso is Rey's mother. After all, the timeline could kind of work — kind of — considering Rogue One's status as a prequel, but the theory smacks of shortsightedness and a troubling assumption that all of the women in Star Wars have to somehow be related.
While I have no doubt that Rey's parentage will indeed be linked to the Skywalkers in some way, making Jyn that link — and perhaps a substitute for Mara Jade, an Expanded Universe character that became Luke's wife and mother of his son, neither of whom currently exist in Disney's canon — would be a disservice to both characters.
Essentially, Jyn would serve a similar purpose as Natalie Portman's Padmé, whose strong will and motivations were tossed aside as soon as she became Luke and Leia's mother. After everything we'd seen from her through three movies, it was hard to believe she could "lose the will to live" when she's got two newborns that are depending on her for survival.
The real reason for this, of course, was to explain her absence in the Original Trilogy. Having a predetermined course limits the arcs a character can undergo, so why introduce a new — and by all appearances interesting — character, only to have her development dependent on what we already expect of her?
One only has to look at Star Wars' own Ahsoka Tano, who was introduced as the never-before-mentioned Padawan of Anakin Skywalker in the period between episodes II and III in Star Wars: The Clone Wars. As a wholly new creation, she was able to rival Luke, Anakin or Han as a character with a well-defined arc that was full of surprises and heartwrenching emotion.
She was a character that fit perfectly into the established canon without ever interrupting it. In fact, it was the opposite: She helped to strengthen Anakin's distrust of the Jedi that ultimately lures him to the Dark Side. Jyn could accomplish a similar feat in a completely different way, by adding a face to the unsung heroes of the Rebellion on the big screen for the first time.
This only works if she's unencumbered by having to give birth to Rey at some point, because then the story becomes about how she winds up with Rey — and probably a relationship — rather than her contributions to the survival of the Rebellion. Of course, it could be both, but Star Wars is in desperate need of a live-action equivalent of Rebels' Hera, who is focused only on the mission and willing to sacrifice personal relationships for it.
As for Rey, tying her to Jyn removes the sense of discovery from her story. Like Luke, Rey's journey to her family needs to be shown through her eyes. By incorporating Jyn into the Skywalker family tapestry, it creates a degree of separation between the viewer and the character that allows us to know something she does not, detaching us from the story.
The intent of the Star Wars anthology movies appears to be to add new elements to the Star Wars tapestry. Not only characters — they're doing movies about Han Solo and probably Boba Fett, after all — but tone, cinematography, editing, and perhaps even genre. We see lots of handheld camerawork in the Rogue One teaser, and it wouldn't be shocking to learn that there are no wipe transitions in the final cut. Tying it so conclusively to the episodic films through Rey and Jyn would lessen its strengths as a standalone movie.
As George Lucas always liked to say, Star Wars is like poetry: There are echoes and rhymes from one movie to the next. Of course there can — and should — be familiar elements, but Rogue One needs to establish its own identity as it's the first example of a new take on the Star Wars Universe; one that can exist free of the Skywalkers and truly expand the galaxy.