Could Kylo and Rey be brother and sister? The immediate thought to the contrary comes from Han's lack of recognition when coming across Rey in the Millennium Falcon. However, playing to the fact that Solo and Leia have clearly been apart for a considerable amount of time - perhaps even immediately after Return of the Jedi, so around 25-30 years - Leia could've very easily shacked up with someone else. The evidence comes from the scene following the destruction of Starkiller base, where just as Rey is wandering out the Falcon, she receives a loving embrace from Leia. The way this scene is shot and the emotion prevalent on Leia's face leads me to believe there's some connection there, as it's not simply a "Well done for surviving" interaction you'd give a new recruit. Rey doesn't know Leia is her mother, and if any parts of the whole "stashed on Jakku for her own safety" theories are true, she's not about to let her in on it either. But the way this scene plays out raises questions as to exactly what Leia knows about Rey, and if she truly recognised her as someone from her own past - not to mention calling her back in a motherly way to see her face one more time, before letting her embark on her next adventure at the close of the film.
